Keep prototype maps in dictionary mode until ICs see them

src/ic/handler-compiler.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/ic/handler-compiler.h"
 
 #include "src/field-type.h"
 #include "src/ic/call-optimization.h"
 #include "src/ic/ic-inl.h"
 #include "src/ic/ic.h"
@@ skipping 426 matching lines @@
   PushVectorAndSlot();
 
   // Check that we are allowed to write this.
   bool is_nonexistent = holder()->map() == transition->GetBackPointer();
   if (is_nonexistent) {
     // Find the top object.
     Handle<JSObject> last;
     PrototypeIterator::WhereToEnd end =
         name->IsPrivate() ? PrototypeIterator::END_AT_NON_HIDDEN
                           : PrototypeIterator::END_AT_NULL;
-    PrototypeIterator iter(isolate(), holder(),
-                           PrototypeIterator::START_AT_PROTOTYPE, end);
+    PrototypeIterator iter(isolate(), holder(), kStartAtPrototype, end);
     while (!iter.IsAtEnd()) {
       last = PrototypeIterator::GetCurrent<JSObject>(iter);
       iter.Advance();
     }
     if (!last.is_null()) set_holder(last);
     NonexistentFrontendHeader(name, &miss, scratch1(), scratch2());
   } else {
     FrontendHeader(receiver(), name, &miss, DONT_RETURN_ANYTHING);
     DCHECK(holder()->HasFastProperties());
   }
@@ skipping 148 matching lines @@
         LoadICState state = LoadICState(kNoExtraICState);
         cached_stub = LoadDictionaryElementStub(isolate(), state).GetCode();
       }
     }
 
     handlers->Add(cached_stub);
   }
 }
 }  // namespace internal
 }  // namespace v8