improve allocation accounting for incremental mark

src/heap/incremental-marking.cc

 // 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.
 
 #include "src/v8.h"
 
 #include "src/heap/incremental-marking.h"
 
 #include "src/code-stubs.h"
 #include "src/compilation-cache.h"
@@ skipping 891 matching lines @@
       }
     }
   }
 }
 
 
 intptr_t IncrementalMarking::Step(intptr_t allocated_bytes,
                                   CompletionAction action,
                                   ForceMarkingAction marking,
                                   ForceCompletionAction completion) {
+  DCHECK(allocated_bytes >= 0);
+
   if (heap_->gc_state() != Heap::NOT_IN_GC || !FLAG_incremental_marking ||
       !FLAG_incremental_marking_steps ||
       (state_ != SWEEPING && state_ != MARKING)) {
     return 0;
   }
 
   allocated_ += allocated_bytes;
 
   if (marking == DO_NOT_FORCE_MARKING && allocated_ < kAllocatedThreshold &&
       write_barriers_invoked_since_last_step_ <
@@ skipping 101 matching lines @@
 void IncrementalMarking::IncrementIdleMarkingDelayCounter() {
   idle_marking_delay_counter_++;
 }
 
 
 void IncrementalMarking::ClearIdleMarkingDelayCounter() {
   idle_marking_delay_counter_ = 0;
 }
 }  // namespace internal
 }  // namespace v8