Move EmbedderHeapTracer::TracePrologue call to the beginning of full gc

include/v8.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.
 
 /** \mainpage V8 API Reference Guide
  *
  * V8 is Google's open source JavaScript engine.
  *
  * This set of documents provides reference material generated from the
  * V8 header file, include/v8.h.
@@ skipping 5461 matching lines @@
   virtual bool AdvanceTracing(double deadline_in_ms,
                               AdvanceTracingActions actions) {
     return false;
   }
   /**
    * V8 will call this method at the end of the gc cycle. Allocation is *not*
    * allowed in the TraceEpilogue.
    */
   virtual void TraceEpilogue() = 0;
 
+  /**
+   * Throw away all intermediate data and reset to the initial state.
+   */
+  virtual void AbortTracing() {}
+
  protected:
   virtual ~EmbedderHeapTracer() = default;
 };
 
 /**
  * Isolate represents an isolated instance of the V8 engine.  V8 isolates have
  * completely separate states.  Objects from one isolate must not be used in
  * other isolates.  The embedder can create multiple isolates and use them in
  * parallel in multiple threads.  An isolate can be entered by at most one
  * thread at any given time.  The Locker/Unlocker API must be used to
@@ skipping 3322 matching lines @@
  */
 
 
 }  // namespace v8
 
 
 #undef TYPE_CHECK
 
 
 #endif  // INCLUDE_V8_H_