[heap] Incremental marking: Fix compile on MIPS

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 95956c8951a02b58c9d6a62c320ecb02e900afec..f585387dc3fa84d5601a39f02e91c868a808c018 100644
--- a/src/heap/incremental-marking.cc
+++ b/src/heap/incremental-marking.cc
@@ -1049,12 +1049,10 @@ double IncrementalMarking::AdvanceIncrementalMarking(
       GCIdleTimeHandler::kIncrementalMarkingStepTimeInMs,
       heap()->tracer()->IncrementalMarkingSpeedInBytesPerMillisecond());
   double remaining_time_in_ms = 0.0;
-  intptr_t bytes_processed = 0;
 
   do {
-    bytes_processed =
-        Step(step_size_in_bytes, step_actions.completion_action,
-             step_actions.force_marking, step_actions.force_completion);
+    Step(step_size_in_bytes, step_actions.completion_action,
+         step_actions.force_marking, step_actions.force_completion);
     remaining_time_in_ms =
         deadline_in_ms - heap()->MonotonicallyIncreasingTimeInMs();
   } while (!heap_->mark_compact_collector()->marking_deque()->IsEmpty() &&