Use entities in js_emitter/model.dart

pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart

Index: pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart
diff --git a/pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart b/pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart
index 0473fe6d0f8758e313559810264398cfca601b63..4847928a9ee44209347293b8f112850fdbb8d1d2 100644
--- a/pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart
+++ b/pkg/compiler/lib/src/js_backend/constant_handler_javascript.dart
@@ -118,7 +118,7 @@ class JavaScriptConstantCompiler extends ConstantCompilerBase
 
   // TODO(johnniwinther): Move this to the backend constant handler.
   /** Caches the statics where the initial value cannot be eagerly compiled. */
-  final Set<VariableElement> lazyStatics = new Set<VariableElement>();
+  final Set<FieldElement> lazyStatics = new Set<FieldElement>();
 
   // Constants computed for constant expressions.
   final Map<Node, ConstantExpression> nodeConstantMap =
@@ -157,8 +157,8 @@ class JavaScriptConstantCompiler extends ConstantCompilerBase
     compiledConstants.add(constant);
   }
 
-  List<VariableElement> getLazilyInitializedFieldsForEmission() {
-    return new List<VariableElement>.from(lazyStatics);
+  List<FieldElement> getLazilyInitializedFieldsForEmission() {
+    return new List<FieldElement>.from(lazyStatics);
   }
 
   /**