Check against the correct type when decoding runtime types.

sdk/lib/_internal/compiler/js_lib/js_mirrors.dart

Index: sdk/lib/_internal/compiler/js_lib/js_mirrors.dart
diff --git a/sdk/lib/_internal/compiler/js_lib/js_mirrors.dart b/sdk/lib/_internal/compiler/js_lib/js_mirrors.dart
index 26882c001666680debf3491f5db4a9dc2db52ee8..4c3bc23f722218cdda09346f28f41d1fa8c0063c 100644
--- a/sdk/lib/_internal/compiler/js_lib/js_mirrors.dart
+++ b/sdk/lib/_internal/compiler/js_lib/js_mirrors.dart
@@ -40,7 +40,8 @@ import 'dart:_js_helper' show
     getRuntimeType,
     runtimeTypeToString,
     setRuntimeTypeInfo,
-    throwInvalidReflectionError;
+    throwInvalidReflectionError,
+    TypeImpl;
 
 import 'dart:_interceptors' show
     Interceptor,
@@ -2675,7 +2676,7 @@ int findTypeVariableIndex(List<TypeVariableMirror> typeVariables, String name) {
 
 TypeMirror typeMirrorFromRuntimeTypeRepresentation(
     DeclarationMirror owner,
-    var /*int|List|JsFunction*/ type) {
+    var /*int|List|JsFunction|TypeImpl*/ type) {
   // TODO(ahe): This method might benefit from using convertRtiToRuntimeType
   // instead of working on strings.
   ClassMirror ownerClass;
@@ -2693,7 +2694,7 @@ TypeMirror typeMirrorFromRuntimeTypeRepresentation(
   String representation;
   if (type == null) {
     return JsMirrorSystem._dynamicType;
-  } else if (type is Type) {
+  } else if (type is TypeImpl) {
     return reflectType(type);
   } else if (ownerClass == null) {
     representation = runtimeTypeToString(type);