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)

10 files changed, 16 insertions, 16 deletions

diff --git a/test/files/neg/override-object-no.check b/test/files/neg/override-object-no.check
index 52bad2b937..9cfda80fc3 100644
--- a/test/files/neg/override-object-no.check
+++ b/test/files/neg/override-object-no.check
@@ -6,8 +6,8 @@ an overriding object must conform to the overridden object's class bound;
                     ^
 override-object-no.scala:21: error: overriding object Bar in trait Quux1 with object Bar in trait Quux2:
 an overriding object must conform to the overridden object's class bound;
- found   : Object{def g: String}
- required: Object{def g: Int}
+ found   : AnyRef{def g: String}
+ required: AnyRef{def g: Int}
   trait Quux2 extends Quux1 { override object Bar { def g = "abc" } } // err
                                               ^
 override-object-no.scala:25: error: overriding object Bar in trait Quux3;
diff --git a/test/files/neg/t2078.check b/test/files/neg/t2078.check
index 3cdaa7d27a..00bb323a0b 100644
--- a/test/files/neg/t2078.check
+++ b/test/files/neg/t2078.check
@@ -1,4 +1,4 @@
-t2078.scala:2: error: contravariant type S occurs in covariant position in type => Object{val x: S} of value f
+t2078.scala:2: error: contravariant type S occurs in covariant position in type => AnyRef{val x: S} of value f
   val f  = new { val x = y }
       ^
 one error found
diff --git a/test/files/neg/t2336.check b/test/files/neg/t2336.check
index 983717469c..28acd4d179 100644
--- a/test/files/neg/t2336.check
+++ b/test/files/neg/t2336.check
@@ -1,4 +1,4 @@
-t2336.scala:6: error: type Foo[Int] is not a stable prefix
+t2336.scala:6: error: Foo[Int] is not a legal prefix for a constructor
   new Foo[Int]#Bar(0)
                ^
 one error found
diff --git a/test/files/neg/t3691.check b/test/files/neg/t3691.check
index bdf6c268b2..6a7e13049a 100644
--- a/test/files/neg/t3691.check
+++ b/test/files/neg/t3691.check
@@ -9,7 +9,7 @@ t3691.scala:5: error: type mismatch;
  val c = (new A[String]{}): { type A } // not ok
           ^
 t3691.scala:7: error: type mismatch;
- found   : Object{type A = String}
+ found   : AnyRef{type A = String}
  required: AnyRef{type A[X]}
  val x = (new { type A = String }): { type A[X] } // not ok
           ^
diff --git a/test/files/neg/t4877.check b/test/files/neg/t4877.check
index a4b1e6a50d..5a2413ca8b 100644
--- a/test/files/neg/t4877.check
+++ b/test/files/neg/t4877.check
@@ -1,10 +1,10 @@
 t4877.scala:4: error: type mismatch;
- found   : Object{def bar: Int}
+ found   : AnyRef{def bar: Int}
  required: AnyRef{def bar: String}
   def foo: AnyRef { def bar: String } = new AnyRef { def bar = 42 }
                                         ^
 t4877.scala:6: error: type mismatch;
- found   : Object{def bar(x: Int): String}
+ found   : AnyRef{def bar(x: Int): String}
  required: AnyRef{def bar(x: Int): Int}
   def foo3: AnyRef { def bar(x: Int): Int } = new AnyRef { def bar(x: Int) = "abc" }
                                               ^
@@ -14,7 +14,7 @@ t4877.scala:7: error: type mismatch;
   def foo4: C { def bar(x: Int): Int ; def quux(x: Int): Int } = new C { def bar(x: Int) = 5 }
                                                                  ^
 t4877.scala:17: error: type mismatch;
- found   : Object{type Mom = String; def bar(x: Int): Int; def bippy(): List[Int]}
+ found   : AnyRef{type Mom = String; def bar(x: Int): Int; def bippy(): List[Int]}
  required: B.this.Bippy
     (which expands to)  AnyRef{type Mom; def bar(x: Int): this.Mom; def bippy(): List[this.Mom]}
   val x: Bippy = new AnyRef {
diff --git a/test/files/neg/t5060.check b/test/files/neg/t5060.check
index e71f30ccdb..09b2d9a4b1 100644
--- a/test/files/neg/t5060.check
+++ b/test/files/neg/t5060.check
@@ -1,7 +1,7 @@
-t5060.scala:2: error: covariant type T occurs in contravariant position in type => Object{def contains(x: T): Unit} of value foo0
+t5060.scala:2: error: covariant type T occurs in contravariant position in type => AnyRef{def contains(x: T): Unit} of value foo0
   val foo0 = {
       ^
-t5060.scala:6: error: covariant type T occurs in contravariant position in type => Object{def contains(x: T): Unit} of method foo1
+t5060.scala:6: error: covariant type T occurs in contravariant position in type => AnyRef{def contains(x: T): Unit} of method foo1
   def foo1 = {
       ^
 two errors found
diff --git a/test/files/neg/t5063.check b/test/files/neg/t5063.check
index 84690d0a1d..c6e553c1b5 100644
--- a/test/files/neg/t5063.check
+++ b/test/files/neg/t5063.check
@@ -1,4 +1,4 @@
-t5063.scala:2: error: value + is not a member of Object
+t5063.scala:2: error: value + is not a member of AnyRef
   super.+("")
         ^
 one error found
diff --git a/test/files/neg/t6436.check b/test/files/neg/t6436.check
index ecb28f9100..5cee6fb558 100644
--- a/test/files/neg/t6436.check
+++ b/test/files/neg/t6436.check
@@ -2,8 +2,8 @@ t6436.scala:8: error: type mismatch;
  found   : StringContext
  required: ?{def q: ?}
 Note that implicit conversions are not applicable because they are ambiguous:
- both method foo1 in object quasiquotes of type (ctx: StringContext)Object{def q: Nothing}
- and method foo2 in object quasiquotes of type (ctx: StringContext)Object{def q: Nothing}
+ both method foo1 in object quasiquotes of type (ctx: StringContext)AnyRef{def q: Nothing}
+ and method foo2 in object quasiquotes of type (ctx: StringContext)AnyRef{def q: Nothing}
  are possible conversion functions from StringContext to ?{def q: ?}
   println(q"a")
           ^
diff --git a/test/files/neg/t6436b.check b/test/files/neg/t6436b.check
index b3c2d73739..21ab972b79 100644
--- a/test/files/neg/t6436b.check
+++ b/test/files/neg/t6436b.check
@@ -2,8 +2,8 @@ t6436b.scala:8: error: type mismatch;
  found   : StringContext
  required: ?{def q: ?}
 Note that implicit conversions are not applicable because they are ambiguous:
- both method foo1 in object quasiquotes of type (ctx: StringContext)Object{def q: Nothing}
- and method foo2 in object quasiquotes of type (ctx: StringContext)Object{def q: Nothing}
+ both method foo1 in object quasiquotes of type (ctx: StringContext)AnyRef{def q: Nothing}
+ and method foo2 in object quasiquotes of type (ctx: StringContext)AnyRef{def q: Nothing}
  are possible conversion functions from StringContext to ?{def q: ?}
   println(StringContext("a").q())
                        ^
diff --git a/test/files/neg/t963.check b/test/files/neg/t963.check
index 1f2d0687b3..4dc202c7bd 100644
--- a/test/files/neg/t963.check
+++ b/test/files/neg/t963.check
@@ -5,7 +5,7 @@ t963.scala:17: error: stable identifier required, but Test.this.y4.x found.
   val w4 : y4.x.type = y4.x
               ^
 t963.scala:10: error: type mismatch;
- found   : Object{def x: Integer}
+ found   : AnyRef{def x: Integer}
  required: AnyRef{val x: Integer}
   val y2 : { val x : java.lang.Integer  } = new { def x = new java.lang.Integer(r.nextInt) }
                                             ^