Do 2 GCs on LowMemoryNotification instead of 7.

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 1297 matching lines @@
   inline bool IsInGCPostProcessing() { return gc_post_processing_depth_ > 0; }
 
 #ifdef DEBUG
   bool IsAllocationAllowed() { return allocation_allowed_; }
   inline bool allow_allocation(bool enable);
 
   bool disallow_allocation_failure() {
     return disallow_allocation_failure_;
   }
 
+  bool flush_eagerly() { return flush_eagerly_; }
+  void set_flush_eagerly(bool to) { flush_eagerly_ = to; }
+
   void TracePathToObjectFrom(Object* target, Object* root);
   void TracePathToObject(Object* target);
   void TracePathToGlobal();
 #endif
 
   // Callback function passed to Heap::Iterate etc.  Copies an object if
   // necessary, the object might be promoted to an old space.  The caller must
   // ensure the precondition that the object is (a) a heap object and (b) in
   // the heap's from space.
   static inline void ScavengePointer(HeapObject** p);
@@ skipping 437 matching lines @@
   // time?
   bool disallow_allocation_failure_;
 
   HeapDebugUtils* debug_utils_;
 #endif  // DEBUG
 
   // Indicates that the new space should be kept small due to high promotion
   // rates caused by the mutator allocating a lot of long-lived objects.
   bool new_space_high_promotion_mode_active_;
 
+  // For emergency memory-freeing GCs.
+  bool flush_eagerly_;
+
   // Limit that triggers a global GC on the next (normally caused) GC.  This
   // is checked when we have already decided to do a GC to help determine
   // which collector to invoke.
   intptr_t old_gen_promotion_limit_;
 
   // Limit that triggers a global GC as soon as is reasonable.  This is
   // checked before expanding a paged space in the old generation and on
   // every allocation in large object space.
   intptr_t old_gen_allocation_limit_;
 
@@ skipping 404 matching lines @@
   inline DisallowAllocationFailure();
   inline ~DisallowAllocationFailure();
 
 #ifdef DEBUG
  private:
   bool old_state_;
 #endif
 };
 
 
+class FlushEagerly {
+ public:
+  inline FlushEagerly();
+  inline ~FlushEagerly();
+
+ private:
+  bool old_state_;
+};
+
+
 class AlwaysAllocateScope {
  public:
   inline AlwaysAllocateScope();
   inline ~AlwaysAllocateScope();
 
  private:
   // Implicitly disable artificial allocation failures.
   DisallowAllocationFailure disallow_allocation_failure_;
 };
 
@@ skipping 591 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_