Make ClassMirror.typeVariables lazy and convert dependencies to native code.

runtime/vm/object.cc

Index: runtime/vm/object.cc
diff --git a/runtime/vm/object.cc b/runtime/vm/object.cc
index b0bfbe8e1e4d469266a949650593e0d1fafc611a..aac3c37ec36f92fc7ddc501723bc757befe8fa2b 100644
--- a/runtime/vm/object.cc
+++ b/runtime/vm/object.cc
@@ -14346,6 +14346,12 @@ RawLibrary* MirrorReference::GetLibraryReferent() const {
 }
 
 
+RawTypeParameter* MirrorReference::GetTypeParameterReferent() const {
+  ASSERT(Object::Handle(referent()).IsTypeParameter());
+  return TypeParameter::Cast(Object::Handle(referent())).raw();
+}
+
+
 RawMirrorReference* MirrorReference::New(const Object& referent,
                                          Heap::Space space) {
   ASSERT(Isolate::Current()->object_store()->mirror_reference_class()