Handle inner classes in RestoreScopes

They need to be entered into their enclosing package scope, because
flatten lifted them out to the toplevel.

Author: odersky

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

@@ -25,7 +25,11 @@ class RestoreScopes extends MiniPhaseTransform with IdentityDenotTransformer { t
     for (stat <- constr :: body)
       if (stat.isInstanceOf[MemberDef] && stat.symbol.exists)
         restoredDecls.enter(stat.symbol)
-    val cinfo = tree.symbol.asClass.classInfo
+    val cls = tree.symbol.asClass
+    cls.owner.asClass.enter(cls) 
+      // Enter class in enclosing package scope, in case it was an inner class before flatten.
+      // For top-level classes this does nothing.
+    val cinfo = cls.classInfo
     tree.symbol.copySymDenotation(
       info = cinfo.derivedClassInfo( // Dotty deviation: Cannot expand cinfo inline without a type error
         decls = restoredDecls: Scope)).installAfter(thisTransform)