[heap] Minor MC: Add evacuation phase

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 2382 matching lines @@
 
 class AlwaysAllocateScope {
  public:
   explicit inline AlwaysAllocateScope(Isolate* isolate);
   inline ~AlwaysAllocateScope();
 
  private:
   Heap* heap_;
 };
 
-
 // Visitor class to verify interior pointers in spaces that do not contain
 // or care about intergenerational references. All heap object pointers have to
 // point into the heap to a location that has a map pointer at its first word.
 // Caveat: Heap::Contains is an approximation because it can return true for
 // objects in a heap space but above the allocation pointer.
 class VerifyPointersVisitor : public ObjectVisitor {
  public:
   inline void VisitPointers(Object** start, Object** end) override;
 };
 
@@ skipping 108 matching lines @@
 class WeakObjectRetainer {
  public:
   virtual ~WeakObjectRetainer() {}
 
   // Return whether this object should be retained. If NULL is returned the
   // object has no references. Otherwise the address of the retained object
   // should be returned as in some GC situations the object has been moved.
   virtual Object* RetainAs(Object* object) = 0;
 };
 
-
 #ifdef DEBUG
 // Helper class for tracing paths to a search target Object from all roots.
 // The TracePathFrom() method can be used to trace paths from a specific
 // object to the search target object.
 class PathTracer : public ObjectVisitor {
  public:
   enum WhatToFind {
     FIND_ALL,   // Will find all matches.
     FIND_FIRST  // Will stop the search after first match.
   };
@@ skipping 96 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_