Support is tests

pkg/compiler/lib/src/js_emitter/program_builder/collector.dart

Index: pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
diff --git a/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart b/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
index b9d53cd4140425ecc2203e4c2247c079b89e8100..2eb33f567802cf9549cc8f3b8e90d191ed0ad375 100644
--- a/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
+++ b/pkg/compiler/lib/src/js_emitter/program_builder/collector.dart
@@ -242,11 +242,11 @@ class Collector {
     // these are thought to not have been instantiated, so we neeed to be able
     // to identify them later and make sure we only emit "empty shells" without
     // fields, etc.
-    classesOnlyNeededForRti = new Set<ClassElement>();
-    for (ClassElement cls in _rtiNeededClasses) {
+    classesOnlyNeededForRti = new Set<ClassEntity>();
+    for (ClassEntity cls in _rtiNeededClasses) {
       while (cls != null && !neededClasses.contains(cls)) {
         if (!classesOnlyNeededForRti.add(cls)) break;
-        cls = cls.superclass;
+        cls = _elementEnvironment.getSuperClass(cls);
       }
     }