[stubs] Introduce a proper ToBooleanStub.

src/heap/heap.h

 // Copyright 2012 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.
 
 #ifndef V8_HEAP_HEAP_H_
 #define V8_HEAP_HEAP_H_
 
 #include <cmath>
 #include <map>
 
@@ skipping 634 matching lines @@
 
   // Trim the given array from the left. Note that this relocates the object
   // start and hence is only valid if there is only a single reference to it.
   FixedArrayBase* LeftTrimFixedArray(FixedArrayBase* obj, int elements_to_trim);
 
   // Trim the given array from the right.
   template<Heap::InvocationMode mode>
   void RightTrimFixedArray(FixedArrayBase* obj, int elements_to_trim);
 
   // Converts the given boolean condition to JavaScript boolean value.
-  inline Object* ToBoolean(bool condition);
+  inline Oddball* ToBoolean(bool condition);
 
   // Check whether the heap is currently iterable.
   bool IsHeapIterable();
 
   // Notify the heap that a context has been disposed.
   int NotifyContextDisposed(bool dependant_context);
 
   void set_native_contexts_list(Object* object) {
     native_contexts_list_ = object;
   }
@@ skipping 1958 matching lines @@
   friend class LargeObjectSpace;
   friend class NewSpace;
   friend class PagedSpace;
   DISALLOW_COPY_AND_ASSIGN(AllocationObserver);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_HEAP_HEAP_H_