Element model cleanup + prepare for easier reimplementation.

pkg/compiler/lib/src/scanner/class_element_parser.dart

Index: pkg/compiler/lib/src/scanner/class_element_parser.dart
diff --git a/pkg/compiler/lib/src/scanner/class_element_parser.dart b/pkg/compiler/lib/src/scanner/class_element_parser.dart
index 0f49ad2ffbb64e047af87675736f93172ce441ce..67fe48035eea7535b9b4f0a7da221e63fea59678 100644
--- a/pkg/compiler/lib/src/scanner/class_element_parser.dart
+++ b/pkg/compiler/lib/src/scanner/class_element_parser.dart
@@ -101,10 +101,10 @@ class PartialClassElement extends ClassElementX with PartialElement {
 }
 
 class MemberListener extends NodeListener {
-  final ClassElement enclosingClass;
+  final ClassElementX enclosingClass;
 
   MemberListener(DiagnosticListener listener,
-                 ClassElement enclosingElement)
+                 ClassElementX enclosingElement)
       : this.enclosingClass = enclosingElement,
         super(listener, enclosingElement.compilationUnit);