Make --stress-compaction more stressful.

src/heap.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1437 matching lines @@
 
   inline void IncrementYoungSurvivorsCounter(int survived) {
     ASSERT(survived >= 0);
     young_survivors_after_last_gc_ = survived;
     survived_since_last_expansion_ += survived;
   }
 
   inline bool NextGCIsLikelyToBeFull() {
     if (FLAG_gc_global) return true;
 
+    if (FLAG_stress_compaction && (gc_count_ & 1) != 0) return true;
+
     intptr_t total_promoted = PromotedTotalSize();
 
     intptr_t adjusted_promotion_limit =
         old_gen_promotion_limit_ - new_space_.Capacity();
 
     if (total_promoted >= adjusted_promotion_limit) return true;
 
     intptr_t adjusted_allocation_limit =
         old_gen_allocation_limit_ - new_space_.Capacity() / 5;
 
@@ skipping 1251 matching lines @@
   AssertNoAllocation no_alloc;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG || LIVE_OBJECT_LIST
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_