Move some code from Runtime_GetPrototype into a new Object::GetPrototype.

src/objects.h

Index: src/objects.h
diff --git a/src/objects.h b/src/objects.h
index 73eaf19e151e7f1bb9e6d85d4f92aeda699b5f66..2f529a730eb1c8151ca4ddd236b7bafd1209b7ca 100644
--- a/src/objects.h
+++ b/src/objects.h
@@ -1290,8 +1290,9 @@ class Object {
       Isolate* isolate, Handle<Object> object, uint32_t index,
       Handle<Object> value, LanguageMode language_mode);
 
-  static inline Handle<Object> GetPrototypeSkipHiddenPrototypes(
-      Isolate* isolate, Handle<Object> receiver);
+  // Get the first non-hidden prototype.
+  static inline Handle<Object> GetPrototype(Isolate* isolate,
+                                            Handle<Object> receiver);
 
   bool HasInPrototypeChain(Isolate* isolate, Object* object);