Make LazyVals respect scope hygiene.

The previius commit on "Refine & for Denotations" caused
NotDefinedHere errors in the backend when compiling dotc/typer.
These were tracked down to three occurrences in LazyVals where `enter` instead
of `enteredAfter` was used. `enter` will enter a symbol in an unknown set of
previous phases. Transformations that traverse scope (like erasedMembers in
TypeErasure will then see the denotations of these symbols outside the
scope in which they are defined.

Author: odersky

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

@@ -175,7 +175,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
         val containerSymbol = ctx.newSymbol(claz, containerName,
           x.symbol.flags &~ containerFlagsMask | containerFlags | Flags.Private,
           tpe, coord = x.symbol.coord
-        ).entered
+        ).enteredAfter(this)
 
         val containerTree = ValDef(containerSymbol, defaultValue(tpe))
         if (x.tpe.isNotNull && tpe <:< defn.ObjectType) { // can use 'null' value instead of flag
@@ -184,7 +184,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
         }
         else {
           val flagName = ctx.freshName(x.name ++ StdNames.nme.BITMAP_PREFIX).toTermName
-          val flagSymbol = ctx.newSymbol(x.symbol.owner, flagName,  containerFlags | Flags.Private, defn.BooleanType).entered
+          val flagSymbol = ctx.newSymbol(x.symbol.owner, flagName,  containerFlags | Flags.Private, defn.BooleanType).enteredAfter(this)
           val flag = ValDef(flagSymbol, Literal(Constants.Constant(false)))
           val slowPath = DefDef(x.symbol.asTerm, mkNonThreadSafeDef(ref(containerSymbol), ref(flagSymbol), x.rhs))
           Thicket(List(containerTree, flag, slowPath))
@@ -331,7 +331,7 @@ class LazyVals extends MiniPhaseTransform with IdentityDenotTransformer {
         }
 
         val containerName = ctx.freshName(x.name ++ StdNames.nme.LAZY_LOCAL).toTermName
-        val containerSymbol = ctx.newSymbol(claz, containerName, (x.mods &~ containerFlagsMask | containerFlags).flags, tpe, coord = x.symbol.coord).entered
+        val containerSymbol = ctx.newSymbol(claz, containerName, (x.mods &~ containerFlagsMask | containerFlags).flags, tpe, coord = x.symbol.coord).enteredAfter(this)
         val containerTree = ValDef(containerSymbol, defaultValue(tpe))
 
         val offset =  ref(companion).ensureApplied.select(offsetSymbol)