Element model cleanup + prepare for easier reimplementation.

pkg/compiler/lib/src/compile_time_constants.dart

Index: pkg/compiler/lib/src/compile_time_constants.dart
diff --git a/pkg/compiler/lib/src/compile_time_constants.dart b/pkg/compiler/lib/src/compile_time_constants.dart
index 6273efa4f519c62bc2993ae10981500b37e2e51a..562fcfdd477a7ef1c8cc708b3993e1ec309d58d3 100644
--- a/pkg/compiler/lib/src/compile_time_constants.dart
+++ b/pkg/compiler/lib/src/compile_time_constants.dart
@@ -1140,7 +1140,7 @@ class ConstructorEvaluator extends CompileTimeConstantEvaluator {
       ClassElement superClass = enclosingClass.superclass;
       if (enclosingClass != compiler.objectClass) {
         assert(superClass != null);
-        assert(superClass.resolutionState == STATE_DONE);
+        assert(superClass.isResolved);
 
         FunctionElement targetConstructor =
             superClass.lookupDefaultConstructor();