Rewrite references to "wtf/" to "platform/wtf/" in platform/heap.

third_party/WebKit/Source/platform/heap/SafePoint.h

 // Copyright 2015 The Chromium 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 SafePoint_h
 #define SafePoint_h
 
 #include "platform/heap/ThreadState.h"
-#include "wtf/ThreadingPrimitives.h"
+#include "platform/wtf/ThreadingPrimitives.h"
 
 namespace blink {
 
 class SafePointScope final {
   STACK_ALLOCATED();
   WTF_MAKE_NONCOPYABLE(SafePointScope);
 
  public:
   explicit SafePointScope(BlinkGC::StackState stackState,
                           ThreadState* state = ThreadState::current())
       : m_state(state) {
     if (m_state) {
       m_state->enterSafePoint(stackState, this);
     }
   }
 
   ~SafePointScope() {
     if (m_state)
       m_state->leaveSafePoint();
   }
 
  private:
   ThreadState* m_state;
 };
 
 }  // namespace blink
 
 #endif