Remove unused lambda capture if DCHECK is not used.

This is a preparation CL to remove -Wno-unused-lambda-capture warning suppression.

Bug: chromium:681136
Change-Id: If3d16c8a6719bf3135e028ab2bafe850778e31b5
Reviewed-on: https://chromium-review.googlesource.com/c/1286390Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56722}

src/heap/incremental-marking.cc

@@ -574,7 +574,12 @@ void IncrementalMarking::UpdateMarkingWorklistAfterScavenge() {
   void* minor_marking_state = nullptr;
 #endif  // ENABLE_MINOR_MC
 
-  marking_worklist()->Update([this, filler_map, minor_marking_state](
+  marking_worklist()->Update([
+#ifdef DEBUG
+                              // this is referred inside DCHECK.
+                                 this,
+#endif
+                                 filler_map, minor_marking_state](
                                  HeapObject* obj, HeapObject** out) -> bool {
     DCHECK(obj->IsHeapObject());
     // Only pointers to from space have to be updated.