Hoist generics-related functions from ClassMirror to TypeMirror.

runtime/lib/mirrors_impl.dart

Index: runtime/lib/mirrors_impl.dart
diff --git a/runtime/lib/mirrors_impl.dart b/runtime/lib/mirrors_impl.dart
index 1e79507fd0c48353b995e7940a27a7702bb29b36..8ae0e48ebddda3f36b530a17f8f8701b0e078403 100644
--- a/runtime/lib/mirrors_impl.dart
+++ b/runtime/lib/mirrors_impl.dart
@@ -1415,9 +1415,14 @@ class _SpecialTypeMirrorImpl extends _LocalMirrorImpl
   final DeclarationMirror owner = null;
   final Symbol simpleName;
   final bool isTopLevel = true;
-  // Fixed length 0, therefore immutable.
   final List<InstanceMirror> metadata = emptyList;
 
+  List<TypeVariableMirror> get typeVariables => emptyList;
+  List<TypeMirror> get typeArguments => emptyList;
+
+  bool get isOriginalDeclaration => true;
+  TypeMirror get originalDeclaration => this;
+
   SourceLocation get location {
     throw new UnimplementedError('TypeMirror.location is not implemented');
   }