Use elements/types in constants/values

pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart

Index: pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart
diff --git a/pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart b/pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart
index a6255d337a9c965083148111cddf8117f57128e4..8cbea7772e82008d98c30982a5658416d438fb49 100644
--- a/pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart
+++ b/pkg/compiler/lib/src/js_emitter/interceptor_stub_generator.dart
@@ -361,9 +361,10 @@ class InterceptorStubGenerator {
     List<ConstantValue> constants =
         handler.getConstantsForEmission(emitter.compareConstants);
     for (ConstantValue constant in constants) {
-      if (constant is TypeConstantValue) {
-        TypeConstantValue typeConstant = constant;
-        Element element = typeConstant.representedType.element;
+      if (constant is TypeConstantValue &&
+          constant.representedType is ResolutionInterfaceType) {
+        ResolutionInterfaceType type = constant.representedType;
+        Element element = type.element;
         if (element is ClassElement) {
           ClassElement classElement = element;
           if (!analysis.needsClass(classElement)) continue;