[heap] Remove unused no marking scope.

src/heap/incremental-marking.cc

Index: src/heap/incremental-marking.cc
diff --git a/src/heap/incremental-marking.cc b/src/heap/incremental-marking.cc
index ffc0ced2b0ec075cf386169de628ae763880cd1a..3f1f037ea5adfef1d9d6cb67c93da96e1bc4e60a 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -39,7 +39,6 @@ IncrementalMarking::IncrementalMarking(Heap* heap)
       allocated_(0),
       write_barriers_invoked_since_last_step_(0),
       idle_marking_delay_counter_(0),
-      no_marking_scope_depth_(0),
       unscanned_bytes_of_large_object_(0),
       was_activated_(false),
       black_allocation_(false),
@@ -1152,8 +1151,6 @@ intptr_t IncrementalMarking::Step(intptr_t allocated_bytes,
     return 0;
   }
 
-  if (state_ == MARKING && no_marking_scope_depth_ > 0) return 0;
-
   intptr_t bytes_processed = 0;
   {
     HistogramTimerScope incremental_marking_scope(