Improve presentation compilation of annotations

A trio of problems were hampering autocompletion of annotations.

First, given that that annotation is written before the annotated
member, it is very common to end parse incomplete code that has a
floating annotation without an anotatee.

The parser was discarding the annotations (ie, the modifiers) and
emitting an `EmptyTree`.

Second, the presetation compiler was only looking for annotations
in the Modifiers of a member def, but after typechecking annotations
are moved into the symbol.

Third, if an annotation failed to typecheck, it was being discarded
in place of `ErroneousAnnotation`.

This commit:
  - modifies the parser to uses a dummy class- or type-def tree,
    instead of EmptyTree, which can carry the annotations.
  - updates the locator to look in the symbol annotations of the
    modifiers contains no annotations.
  - uses a separate instance of `ErroneousAnnotation` for each
    erroneous annotation, and stores the original tree in its
    `original` tree.

1 files changed, 0 insertions, 1 deletions

diff --git a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
index 5477bdd6d4..7725e4a2f0 100644
--- a/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
+++ b/src/reflect/scala/reflect/runtime/JavaUniverseForce.scala
@@ -106,7 +106,6 @@ trait JavaUniverseForce { self: runtime.JavaUniverse  =>
     this.AnnotationInfo
     this.Annotation
     this.UnmappableAnnotation
-    this.ErroneousAnnotation
     this.ThrownException
     this.typeNames
     this.tpnme