Remove some asserts to speed up debug mode.

src/incremental-marking.cc

 // Copyright 2011 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 723 matching lines @@
         // We will mark cache black with a separate pass
         // when we finish marking.
         MarkObjectGreyDoNotEnqueue(ctx->normalized_map_cache());
 
         VisitGlobalContext(ctx, &marking_visitor);
       } else {
         obj->IterateBody(map->instance_type(), size, &marking_visitor);
       }
 
       MarkBit obj_mark_bit = Marking::MarkBitFrom(obj);
-      ASSERT(Marking::IsGrey(obj_mark_bit) ||
-             (obj->IsFiller() && Marking::IsWhite(obj_mark_bit)));
       Marking::MarkBlack(obj_mark_bit);
       MemoryChunk::IncrementLiveBytes(obj->address(), size);
     }
     if (marking_deque_.IsEmpty()) MarkingComplete();
   }
 
   allocated_ = 0;
 
   steps_count_++;
   steps_count_since_last_gc_++;
@@ skipping 55 matching lines @@
   bytes_rescanned_ = 0;
   allocation_marking_factor_ = kInitialAllocationMarkingFactor;
 }
 
 
 int64_t IncrementalMarking::SpaceLeftInOldSpace() {
   return heap_->MaxOldGenerationSize() - heap_->PromotedSpaceSize();
 }
 
 } }  // namespace v8::internal