Backport of SI-6846.

Squashed commit of the following:

commit 55806cc0e6177820c12a35a18b4f2a12dc07bb39
Author: Paul Phillips <paulp@improving.org>
Date:   Wed Dec 19 07:32:19 2012 -0800

    SI-6846, regression in type constructor inference.

    In 658ba1b4e6 some inference was gained and some was lost.
    In this commit we regain what was lost and gain even more.
    Dealiasing and widening should be fully handled now, as
    illustrated by the test case.
    (cherry picked from commit dbebcd509e4013ce02655a2687b27d0967b3650e)

commit e6ef58447d0f4ef6de956fcc03ee283bb9028c02
Author: Paul Phillips <paulp@improving.org>
Date:   Fri Dec 21 15:11:29 2012 -0800

    Cleaning up type alias usage.

    I determined that many if not most of the calls to .normalize
    have no intent beyond dealiasing the type. In light of this I
    went call site to call site knocking on doors and asking why
    exactly they were calling any of

      .normalize
      .widen.normalize
      .normalize.widen

    and if I didn't like their answers they found themselves
    introduced to 'dropAliasesAndSingleTypes', the recursive widener
    and dealiaser which I concluded is necessary after all.

    Discovered that the object called 'deAlias' actually depends
    upon calling 'normalize', not 'dealias'. Decided this was
    sufficient cause to rename it to 'normalizeAliases'.

    Created dealiasWiden and dealiasWidenChain.

    Dropped dropAliasesAndSingleTypes in favor of methods
    on Type alongside dealias and widen (Type#dealiasWiden).
    These should reduce the number of "hey, the type alias doesn't work" bugs.

    (cherry picked from commit 3bf51189f979eb0dd41744ca844fd12dfdaa0dee)

    Conflicts:
    	src/compiler/scala/tools/nsc/interpreter/CompletionOutput.scala

commit c1d8803cea1523f458730103386d8e14324a9446
Author: Paul Phillips <paulp@improving.org>
Date:   Sat Dec 22 08:13:48 2012 -0800

    Shored up a hidden dealiasing dependency.

    Like the comment says:

    // This way typedNew always returns a dealiased type. This
    // used to happen by accident for instantiations without type
    // arguments due to ad hoc code in typedTypeConstructor, and
    // annotations depended on it (to the extent that they worked,
    // which they did not when given a parameterized type alias
    // which dealiased to an annotation.) typedTypeConstructor
    // dealiases nothing now, but it makes sense for a "new" to
    // always be given a dealiased type.

    PS:
    Simply running the test suite is becoming more difficult all
    the time. Running "ant test" includes time consuming activities
    of niche interest such as all the osgi tests, but test.suite
    manages to miss the continuations tests.
    (cherry picked from commit 422f461578ae0547181afe6d2c0c52ea1071d37b)

commit da4748502792b260161baa10939554564c488051
Author: Paul Phillips <paulp@improving.org>
Date:   Fri Dec 21 12:39:02 2012 -0800

    Fix and simplify typedTypeConstructor.

    Investigating the useful output of devWarning (-Xdev people,
    it's good for you) led back to this comment:

      "normalize to get rid of type aliases"

    You may know that this is not all the normalizing does.
    Normalizing also turns TypeRefs with unapplied arguments
    (type constructors) into PolyTypes. That means that when
    typedParentType would call typedTypeConstructor it would
    find its parent had morphed into a PolyType. Not that it
    noticed; it would blithely continue and unwittingly discard
    the type arguments by way of appliedType (which smoothly
    logged the incident, thank you appliedType.)

    The simplification of typedTypeConstructor:

    There was a whole complicated special treatment of AnyRef
    here which appears to have become unnecessary. Removed special
    treatment and lit a candle for regularity.

    Updated lots of tests regarding newly not-so-special AnyRef.
    (cherry picked from commit 394cc426c1ff1da53146679b4e2995ece52a133e)

commit 1f3c77bacb2fbb3ba9e4ad0a8a733e0f9263b234
Author: Paul Phillips <paulp@improving.org>
Date:   Fri Dec 21 15:06:10 2012 -0800

    Removed dead implementation.

    Another "attractive nuisance" burning off time until I
    realized it was commented out.
    (cherry picked from commit ed40f5cbdf35d09b02898e9c0950b9bd34c1f858)

13 files changed, 70 insertions, 70 deletions

diff --git a/test/files/run/existentials-in-compiler.check b/test/files/run/existentials-in-compiler.check
index 4df4b0ca96..0d7a9298b4 100644
--- a/test/files/run/existentials-in-compiler.check
+++ b/test/files/run/existentials-in-compiler.check
@@ -1,156 +1,156 @@
-abstract trait Bippy[A <: AnyRef, B] extends Object
+abstract trait Bippy[A <: AnyRef, B] extends AnyRef
     extest.Bippy[_ <: AnyRef, _]
 
-abstract trait BippyBud[A <: AnyRef, B, C <: List[A]] extends Object
+abstract trait BippyBud[A <: AnyRef, B, C <: List[A]] extends AnyRef
     extest.BippyBud[A,B,C] forSome { A <: AnyRef; B; C <: List[A] }
 
-abstract trait BippyLike[A <: AnyRef, B <: List[A], This <: extest.BippyLike[A,B,This] with extest.Bippy[A,B]] extends Object
+abstract trait BippyLike[A <: AnyRef, B <: List[A], This <: extest.BippyLike[A,B,This] with extest.Bippy[A,B]] extends AnyRef
     extest.BippyLike[A,B,This] forSome { A <: AnyRef; B <: List[A]; This <: extest.BippyLike[A,B,This] with extest.Bippy[A,B] }
 
-abstract trait Contra[-A >: AnyRef, -B] extends Object
+abstract trait Contra[-A >: AnyRef, -B] extends AnyRef
     extest.Contra[_ >: AnyRef, _]
 
-abstract trait ContraLike[-A >: AnyRef, -B >: List[A]] extends Object
+abstract trait ContraLike[-A >: AnyRef, -B >: List[A]] extends AnyRef
     extest.ContraLike[A,B] forSome { -A >: AnyRef; -B >: List[A] }
 
-abstract trait Cov01[+A <: AnyRef, +B] extends Object
+abstract trait Cov01[+A <: AnyRef, +B] extends AnyRef
     extest.Cov01[_ <: AnyRef, _]
 
-abstract trait Cov02[+A <: AnyRef, B] extends Object
+abstract trait Cov02[+A <: AnyRef, B] extends AnyRef
     extest.Cov02[_ <: AnyRef, _]
 
-abstract trait Cov03[+A <: AnyRef, -B] extends Object
+abstract trait Cov03[+A <: AnyRef, -B] extends AnyRef
     extest.Cov03[_ <: AnyRef, _]
 
-abstract trait Cov04[A <: AnyRef, +B] extends Object
+abstract trait Cov04[A <: AnyRef, +B] extends AnyRef
     extest.Cov04[_ <: AnyRef, _]
 
-abstract trait Cov05[A <: AnyRef, B] extends Object
+abstract trait Cov05[A <: AnyRef, B] extends AnyRef
     extest.Cov05[_ <: AnyRef, _]
 
-abstract trait Cov06[A <: AnyRef, -B] extends Object
+abstract trait Cov06[A <: AnyRef, -B] extends AnyRef
     extest.Cov06[_ <: AnyRef, _]
 
-abstract trait Cov07[-A <: AnyRef, +B] extends Object
+abstract trait Cov07[-A <: AnyRef, +B] extends AnyRef
     extest.Cov07[_ <: AnyRef, _]
 
-abstract trait Cov08[-A <: AnyRef, B] extends Object
+abstract trait Cov08[-A <: AnyRef, B] extends AnyRef
     extest.Cov08[_ <: AnyRef, _]
 
-abstract trait Cov09[-A <: AnyRef, -B] extends Object
+abstract trait Cov09[-A <: AnyRef, -B] extends AnyRef
     extest.Cov09[_ <: AnyRef, _]
 
-abstract trait Cov11[+A <: AnyRef, +B <: List[_]] extends Object
+abstract trait Cov11[+A <: AnyRef, +B <: List[_]] extends AnyRef
     extest.Cov11[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov12[+A <: AnyRef, B <: List[_]] extends Object
+abstract trait Cov12[+A <: AnyRef, B <: List[_]] extends AnyRef
     extest.Cov12[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov13[+A <: AnyRef, -B <: List[_]] extends Object
+abstract trait Cov13[+A <: AnyRef, -B <: List[_]] extends AnyRef
     extest.Cov13[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov14[A <: AnyRef, +B <: List[_]] extends Object
+abstract trait Cov14[A <: AnyRef, +B <: List[_]] extends AnyRef
     extest.Cov14[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov15[A <: AnyRef, B <: List[_]] extends Object
+abstract trait Cov15[A <: AnyRef, B <: List[_]] extends AnyRef
     extest.Cov15[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov16[A <: AnyRef, -B <: List[_]] extends Object
+abstract trait Cov16[A <: AnyRef, -B <: List[_]] extends AnyRef
     extest.Cov16[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov17[-A <: AnyRef, +B <: List[_]] extends Object
+abstract trait Cov17[-A <: AnyRef, +B <: List[_]] extends AnyRef
     extest.Cov17[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov18[-A <: AnyRef, B <: List[_]] extends Object
+abstract trait Cov18[-A <: AnyRef, B <: List[_]] extends AnyRef
     extest.Cov18[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov19[-A <: AnyRef, -B <: List[_]] extends Object
+abstract trait Cov19[-A <: AnyRef, -B <: List[_]] extends AnyRef
     extest.Cov19[_ <: AnyRef, _ <: List[_]]
 
-abstract trait Cov21[+A, +B] extends Object
+abstract trait Cov21[+A, +B] extends AnyRef
     extest.Cov21[_, _]
 
-abstract trait Cov22[+A, B] extends Object
+abstract trait Cov22[+A, B] extends AnyRef
     extest.Cov22[_, _]
 
-abstract trait Cov23[+A, -B] extends Object
+abstract trait Cov23[+A, -B] extends AnyRef
     extest.Cov23[_, _]
 
-abstract trait Cov24[A, +B] extends Object
+abstract trait Cov24[A, +B] extends AnyRef
     extest.Cov24[_, _]
 
-abstract trait Cov25[A, B] extends Object
+abstract trait Cov25[A, B] extends AnyRef
     extest.Cov25[_, _]
 
-abstract trait Cov26[A, -B] extends Object
+abstract trait Cov26[A, -B] extends AnyRef
     extest.Cov26[_, _]
 
-abstract trait Cov27[-A, +B] extends Object
+abstract trait Cov27[-A, +B] extends AnyRef
     extest.Cov27[_, _]
 
-abstract trait Cov28[-A, B] extends Object
+abstract trait Cov28[-A, B] extends AnyRef
     extest.Cov28[_, _]
 
-abstract trait Cov29[-A, -B] extends Object
+abstract trait Cov29[-A, -B] extends AnyRef
     extest.Cov29[_, _]
 
-abstract trait Cov31[+A, +B, C <: (A, B)] extends Object
+abstract trait Cov31[+A, +B, C <: (A, B)] extends AnyRef
     extest.Cov31[A,B,C] forSome { +A; +B; C <: (A, B) }
 
-abstract trait Cov32[+A, B, C <: (A, B)] extends Object
+abstract trait Cov32[+A, B, C <: (A, B)] extends AnyRef
     extest.Cov32[A,B,C] forSome { +A; B; C <: (A, B) }
 
-abstract trait Cov33[+A, -B, C <: Tuple2[A, _]] extends Object
+abstract trait Cov33[+A, -B, C <: Tuple2[A, _]] extends AnyRef
     extest.Cov33[A,B,C] forSome { +A; -B; C <: Tuple2[A, _] }
 
-abstract trait Cov34[A, +B, C <: (A, B)] extends Object
+abstract trait Cov34[A, +B, C <: (A, B)] extends AnyRef
     extest.Cov34[A,B,C] forSome { A; +B; C <: (A, B) }
 
-abstract trait Cov35[A, B, C <: (A, B)] extends Object
+abstract trait Cov35[A, B, C <: (A, B)] extends AnyRef
     extest.Cov35[A,B,C] forSome { A; B; C <: (A, B) }
 
-abstract trait Cov36[A, -B, C <: Tuple2[A, _]] extends Object
+abstract trait Cov36[A, -B, C <: Tuple2[A, _]] extends AnyRef
     extest.Cov36[A,B,C] forSome { A; -B; C <: Tuple2[A, _] }
 
-abstract trait Cov37[-A, +B, C <: Tuple2[_, B]] extends Object
+abstract trait Cov37[-A, +B, C <: Tuple2[_, B]] extends AnyRef
     extest.Cov37[A,B,C] forSome { -A; +B; C <: Tuple2[_, B] }
 
-abstract trait Cov38[-A, B, C <: Tuple2[_, B]] extends Object
+abstract trait Cov38[-A, B, C <: Tuple2[_, B]] extends AnyRef
     extest.Cov38[A,B,C] forSome { -A; B; C <: Tuple2[_, B] }
 
-abstract trait Cov39[-A, -B, C <: Tuple2[_, _]] extends Object
+abstract trait Cov39[-A, -B, C <: Tuple2[_, _]] extends AnyRef
     extest.Cov39[_, _, _ <: Tuple2[_, _]]
 
-abstract trait Cov41[+A >: Null, +B] extends Object
+abstract trait Cov41[+A >: Null, +B] extends AnyRef
     extest.Cov41[_ >: Null, _]
 
-abstract trait Cov42[+A >: Null, B] extends Object
+abstract trait Cov42[+A >: Null, B] extends AnyRef
     extest.Cov42[_ >: Null, _]
 
-abstract trait Cov43[+A >: Null, -B] extends Object
+abstract trait Cov43[+A >: Null, -B] extends AnyRef
     extest.Cov43[_ >: Null, _]
 
-abstract trait Cov44[A >: Null, +B] extends Object
+abstract trait Cov44[A >: Null, +B] extends AnyRef
     extest.Cov44[_ >: Null, _]
 
-abstract trait Cov45[A >: Null, B] extends Object
+abstract trait Cov45[A >: Null, B] extends AnyRef
     extest.Cov45[_ >: Null, _]
 
-abstract trait Cov46[A >: Null, -B] extends Object
+abstract trait Cov46[A >: Null, -B] extends AnyRef
     extest.Cov46[_ >: Null, _]
 
-abstract trait Cov47[-A >: Null, +B] extends Object
+abstract trait Cov47[-A >: Null, +B] extends AnyRef
     extest.Cov47[_ >: Null, _]
 
-abstract trait Cov48[-A >: Null, B] extends Object
+abstract trait Cov48[-A >: Null, B] extends AnyRef
     extest.Cov48[_ >: Null, _]
 
-abstract trait Cov49[-A >: Null, -B] extends Object
+abstract trait Cov49[-A >: Null, -B] extends AnyRef
     extest.Cov49[_ >: Null, _]
 
-abstract trait Covariant[+A <: AnyRef, +B] extends Object
+abstract trait Covariant[+A <: AnyRef, +B] extends AnyRef
     extest.Covariant[_ <: AnyRef, _]
 
-abstract trait CovariantLike[+A <: AnyRef, +B <: List[A], +This <: extest.CovariantLike[A,B,This] with extest.Covariant[A,B]] extends Object
+abstract trait CovariantLike[+A <: AnyRef, +B <: List[A], +This <: extest.CovariantLike[A,B,This] with extest.Covariant[A,B]] extends AnyRef
     extest.CovariantLike[A,B,This] forSome { +A <: AnyRef; +B <: List[A]; +This <: extest.CovariantLike[A,B,This] with extest.Covariant[A,B] }
 
diff --git a/test/files/run/existentials3-new.check b/test/files/run/existentials3-new.check
index 00614b19db..8f7dd701ac 100644
--- a/test/files/run/existentials3-new.check
+++ b/test/files/run/existentials3-new.check
@@ -7,7 +7,7 @@ Test.ToS, t=RefinedType, s=f5
 () => Test.ToS, t=TypeRef, s=trait Function0
 $anon, t=TypeRef, s=type $anon
 $anon, t=TypeRef, s=type $anon
-List[java.lang.Object{type T1}#T1], t=TypeRef, s=class List
+List[AnyRef{type T1}#T1], t=TypeRef, s=class List
 List[Seq[Int]], t=TypeRef, s=class List
 List[Seq[U forSome { type U <: Int }]], t=TypeRef, s=class List
 Bar.type, t=TypeRef, s=type Bar.type
@@ -19,6 +19,6 @@ Test.ToS, t=RefinedType, s=g5
 () => Test.ToS, t=TypeRef, s=trait Function0
 $anon, t=TypeRef, s=type $anon
 $anon, t=TypeRef, s=type $anon
-List[java.lang.Object{type T1}#T1], t=TypeRef, s=class List
+List[AnyRef{type T1}#T1], t=TypeRef, s=class List
 List[Seq[Int]], t=TypeRef, s=class List
 List[Seq[U forSome { type U <: Int }]], t=TypeRef, s=class List
diff --git a/test/files/run/existentials3-old.check b/test/files/run/existentials3-old.check
index 72abfac637..36a458dacc 100644
--- a/test/files/run/existentials3-old.check
+++ b/test/files/run/existentials3-old.check
@@ -5,7 +5,7 @@ Object with Test$ToS
 Object with Test$ToS
 scala.Function0[Object with Test$ToS]
 scala.Function0[Object with Test$ToS]
-_ <: Object with _ <: Object with Test$ToS
+_ <: Object with _ <: Object with Object with Test$ToS
 _ <: Object with _ <: Object with _ <: Object with Test$ToS
 scala.collection.immutable.List[Object with scala.collection.Seq[Int]]
 scala.collection.immutable.List[Object with scala.collection.Seq[_ <: Int]]
@@ -16,7 +16,7 @@ Object with Test$ToS
 Object with Test$ToS
 scala.Function0[Object with Test$ToS]
 scala.Function0[Object with Test$ToS]
-_ <: Object with _ <: Object with Test$ToS
+_ <: Object with _ <: Object with Object with Test$ToS
 _ <: Object with _ <: Object with _ <: Object with Test$ToS
 scala.collection.immutable.List[Object with scala.collection.Seq[Int]]
 scala.collection.immutable.List[Object with scala.collection.Seq[_ <: Int]]
diff --git a/test/files/run/macro-declared-in-trait.check b/test/files/run/macro-declared-in-trait.check
index 104ff1e99b..0d70ac74f3 100644
--- a/test/files/run/macro-declared-in-trait.check
+++ b/test/files/run/macro-declared-in-trait.check
@@ -1,5 +1,5 @@
 prefix = Expr[Nothing]({
-  final class $anon extends Object with Base {
+  final class $anon extends AnyRef with Base {
     def <init>(): anonymous class $anon = {
       $anon.super.<init>();
       ()
diff --git a/test/files/run/reflection-equality.check b/test/files/run/reflection-equality.check
index 17c1f6dd70..65b525731f 100644
--- a/test/files/run/reflection-equality.check
+++ b/test/files/run/reflection-equality.check
@@ -24,7 +24,7 @@ cs: reflect.runtime.universe.ClassSymbol = class X
 
 scala> val ts: Type = cs.typeSignature
 ts: reflect.runtime.universe.Type = 
-java.lang.Object {
+scala.AnyRef {
   def <init>(): X
   def methodIntIntInt(x: scala.Int,y: scala.Int): scala.Int
 }
diff --git a/test/files/run/repl-colon-type.check b/test/files/run/repl-colon-type.check
index 35cd04ba87..56ddd74375 100644
--- a/test/files/run/repl-colon-type.check
+++ b/test/files/run/repl-colon-type.check
@@ -77,10 +77,10 @@ scala> :type -v List(1,2,3) filter _
 
 // Internal Type structure
 TypeRef(
-  TypeSymbol(abstract trait Function1[-T1, +R] extends Object)
+  TypeSymbol(abstract trait Function1[-T1, +R] extends AnyRef)
   args = List(
     TypeRef(
-      TypeSymbol(abstract trait Function1[-T1, +R] extends Object)
+      TypeSymbol(abstract trait Function1[-T1, +R] extends AnyRef)
       args = List(
         TypeRef(TypeSymbol(final abstract class Int extends AnyVal))
         TypeRef(
@@ -147,7 +147,7 @@ Int => Iterator[List[Nothing]]
 
 // Internal Type structure
 TypeRef(
-  TypeSymbol(abstract trait Function1[-T1, +R] extends Object)
+  TypeSymbol(abstract trait Function1[-T1, +R] extends AnyRef)
   args = List(
     TypeRef(TypeSymbol(final abstract class Int extends AnyVal))
     TypeRef(
@@ -180,7 +180,7 @@ PolyType(
   typeParams = List(TypeParam(T <: AnyVal))
   resultType = NullaryMethodType(
     TypeRef(
-      TypeSymbol(abstract trait Function1[-T1, +R] extends Object)
+      TypeSymbol(abstract trait Function1[-T1, +R] extends AnyRef)
       args = List(
         TypeRef(TypeSymbol(final abstract class Int extends AnyVal))
         TypeRef(
diff --git a/test/files/run/repl-parens.check b/test/files/run/repl-parens.check
index 4b7ce6b059..15f4b4524a 100644
--- a/test/files/run/repl-parens.check
+++ b/test/files/run/repl-parens.check
@@ -66,7 +66,7 @@ scala> 55 ; () => 5
 res13: () => Int = <function0>
 
 scala> () => { class X ; new X }
-res14: () => Object = <function0>
+res14: () => AnyRef = <function0>
 
 scala> 
 
diff --git a/test/files/run/t4172.check b/test/files/run/t4172.check
index f16c9e5151..94cdff4870 100644
--- a/test/files/run/t4172.check
+++ b/test/files/run/t4172.check
@@ -5,7 +5,7 @@ scala>
 
 scala>     val c = { class C { override def toString = "C" }; ((new C, new C { def f = 2 })) }
 warning: there were 1 feature warnings; re-run with -feature for details
-c: (C, C{def f: Int}) forSome { type C <: Object } = (C,C)
+c: (C, C{def f: Int}) forSome { type C <: AnyRef } = (C,C)
 
 scala> 
 
diff --git a/test/files/run/t5256a.check b/test/files/run/t5256a.check
index 7e60139db3..09b5a02831 100644
--- a/test/files/run/t5256a.check
+++ b/test/files/run/t5256a.check
@@ -1,6 +1,6 @@
 class A
 A
-Object {
+AnyRef {
   def <init>(): A
   def foo: Nothing
 }
diff --git a/test/files/run/t5256b.check b/test/files/run/t5256b.check
index a80df6eb30..ca93aaa706 100644
--- a/test/files/run/t5256b.check
+++ b/test/files/run/t5256b.check
@@ -1,6 +1,6 @@
 class A
 Test.A
-Object {
+AnyRef {
   def <init>(): Test.A
   def foo: Nothing
 }
diff --git a/test/files/run/t5256d.check b/test/files/run/t5256d.check
index 9742ae572e..b7617e80a2 100644
--- a/test/files/run/t5256d.check
+++ b/test/files/run/t5256d.check
@@ -22,7 +22,7 @@ scala> println(c.fullName)
 $line8.$read.$iw.$iw.$iw.$iw.A
 
 scala> println(c.typeSignature)
-java.lang.Object {
+scala.AnyRef {
   def <init>(): A
   def foo: scala.Nothing
 }
diff --git a/test/files/run/t5256e.check b/test/files/run/t5256e.check
index 011115720c..ed3513183e 100644
--- a/test/files/run/t5256e.check
+++ b/test/files/run/t5256e.check
@@ -1,6 +1,6 @@
 class A
 Test.C.A
-Object {
+AnyRef {
   def <init>(): C.this.A
   def foo: Nothing
 }
diff --git a/test/files/run/t5256f.check b/test/files/run/t5256f.check
index e0fec85596..6a89d0b86a 100644
--- a/test/files/run/t5256f.check
+++ b/test/files/run/t5256f.check
@@ -1,12 +1,12 @@
 class A1
 Test.A1
-Object {
+AnyRef {
   def <init>(): Test.A1
   def foo: Nothing
 }
 class A2
 Test.A2
-Object {
+AnyRef {
   def <init>(): Test.this.A2
   def foo: Nothing
 }