Added a promotion queue unit test that test promotion queue memory corruption

src/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_H_
 #define V8_HEAP_H_
 
 #include <cmath>
 
 #include "src/allocation.h"
@@ skipping 407 matching lines @@
     ASSERT(GetHeadPage() == Page::FromAllocationTop(limit));
     limit_ = reinterpret_cast<intptr_t*>(limit);
 
     if (limit_ <= rear_) {
       return;
     }
 
     RelocateQueueHead();
   }
 
+  bool IsBelowPromotionQueue(Address to_space_top) {
+    // If the given to-space top pointer and the head of the promotion queue
+    // are not on the same page, then the to-space objects are below the
+    // promotion queue.
+    if (GetHeadPage() != Page::FromAddress(to_space_top)) {
+      return true;
+    }
+    // If the to space top pointer is smaller or equal than the promotion
+    // queue head, then the to-space objects are below the promotion queue.
+    return reinterpret_cast<intptr_t*>(to_space_top) <= rear_;
+  }
+
   bool is_empty() {
     return (front_ == rear_) &&
         (emergency_stack_ == NULL || emergency_stack_->length() == 0);
   }
 
   inline void insert(HeapObject* target, int size);
 
   void remove(HeapObject** target, int* size) {
     ASSERT(!is_empty());
     if (front_ == rear_) {
@@ skipping 2327 matching lines @@
   DisallowHeapAllocation no_allocation;  // i.e. no gc allowed.
 
  private:
   DISALLOW_IMPLICIT_CONSTRUCTORS(PathTracer);
 };
 #endif  // DEBUG
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_H_