Introduce a PrototypeIterator class and use it for prototype access

src/string-stream.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/string-stream.h"
 
 #include "src/handles-inl.h"
+#include "src/prototype.h"
 
 namespace v8 {
 namespace internal {
 
 static const int kMentionedObjectCacheMaxSize = 256;
 
 char* HeapStringAllocator::allocate(unsigned bytes) {
   space_ = NewArray<char>(bytes);
   return space_;
 }
@@ skipping 474 matching lines @@
     Add("%o", f);
     Add("/* warning: no JSFunction object or function name found */ ");
   }
 }
 
 
 void StringStream::PrintPrototype(JSFunction* fun, Object* receiver) {
   Object* name = fun->shared()->name();
   bool print_name = false;
   Isolate* isolate = fun->GetIsolate();
-  for (Object* p = receiver;
-       p != isolate->heap()->null_value();
-       p = p->GetPrototype(isolate)) {
-    if (p->IsJSObject()) {
-      Object* key = JSObject::cast(p)->SlowReverseLookup(fun);
+  for (PrototypeIterator iter(isolate, receiver,
+                              PrototypeIterator::START_AT_RECEIVER);
+       !iter.IsAtEnd(); iter.Advance()) {
+    if (iter.GetCurrent()->IsJSObject()) {
+      Object* key = JSObject::cast(iter.GetCurrent())->SlowReverseLookup(fun);
       if (key != isolate->heap()->undefined_value()) {
         if (!name->IsString() ||
             !key->IsString() ||
             !String::cast(name)->Equals(String::cast(key))) {
           print_name = true;
         }
         if (name->IsString() && String::cast(name)->length() == 0) {
           print_name = false;
         }
         name = key;
@@ skipping 25 matching lines @@
   }
   MemCopy(new_space, space_, *bytes);
   *bytes = new_bytes;
   DeleteArray(space_);
   space_ = new_space;
   return new_space;
 }
 
 
 } }  // namespace v8::internal