Add faster, but unsafe version of LoadInternalField.

include/v8-experimental.h

 // Copyright 2015 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.
 
 /**
  * This header contains a set of experimental V8 APIs. We hope these will
  * become a part of standard V8, but they may also be removed if we deem the
  * experiment to not be successul.
  */
 #ifndef V8_INCLUDE_V8_EXPERIMENTAL_H_
@@ skipping 13 matching lines @@
   };
   struct LabelId {
     size_t label_id;
   };
 
   static FastAccessorBuilder* New(Isolate* isolate);
 
   ValueId IntegerConstant(int int_constant);
   ValueId GetReceiver();
   ValueId LoadInternalField(ValueId value_id, int field_no);
+  ValueId LoadInternalFieldUnsafe(ValueId value_id, int field_no);
   ValueId LoadValue(ValueId value_id, int offset);
   ValueId LoadObject(ValueId value_id, int offset);
   void ReturnValue(ValueId value_id);
   void CheckFlagSetOrReturnNull(ValueId value_id, int mask);
   void CheckNotZeroOrReturnNull(ValueId value_id);
   LabelId MakeLabel();
   void SetLabel(LabelId label_id);
   void CheckNotZeroOrJump(ValueId value_id, LabelId label_id);
   ValueId Call(v8::FunctionCallback callback, ValueId value_id);
 
  private:
   FastAccessorBuilder() = delete;
   FastAccessorBuilder(const FastAccessorBuilder&) = delete;
   ~FastAccessorBuilder() = delete;
   void operator=(const FastAccessorBuilder&) = delete;
 };
 
 }  // namespace experimental
 }  // namespace v8
 
 #endif  // V8_INCLUDE_V8_EXPERIMENTAL_H_