Make elimWildcardIdents apply to Assignments

Fixes junit failure in dotty where a lazy val was initialized with
a "...$lazy = _" assignment.

Moved ElimWiildcard to one group before. It does not really matter where it goes
so it might as well go someshere in the middle of the pack.

Author: odersky

src/dotty/tools/dotc/Compiler.scala

@@ -71,12 +71,12 @@ class Compiler {
       List(new LambdaLift,   // in this mini-phase block scopes are incorrect. No phases that rely on scopes should be here
            new Flatten,
            new ElimStaticThis,
+           new ElimWildcardIdents,
            new RestoreScopes),
       List(/*new PrivateToStatic,*/
            new ExpandPrivate,
            new CollectEntryPoints,
            new LabelDefs,
-           new ElimWildcardIdents,
            new TraitConstructors),
       List(new GenBCode)
     )

src/dotty/tools/dotc/transform/ElimWildcardIdents.scala

@@ -29,6 +29,9 @@ class ElimWildcardIdents extends MiniPhaseTransform {
     recur(tree)
   }
 
+  override def transformAssign(tree: tpd.Assign)(implicit ctx: Context, info: TransformerInfo): tpd.Tree =
+    cpy.Assign(tree)(tree.lhs, wildcardToDefaultValue(tree.rhs))
+
   override def transformValDef(tree: tpd.ValDef)(implicit ctx: Context, info: TransformerInfo): tpd.Tree =
     cpy.ValDef(tree)(rhs = wildcardToDefaultValue(tree.rhs))