[heap] Guard VerifyCountersAfterSweeping with ifdef DEBUG.

VERIFY_HEAP does not necessarily imply DEBUG.

Bug: chromium:694255
TRB: mlippautz@chromium.org
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I1699288bd9d826ea1d577dd4fc2de81ee450add7
Reviewed-on: https://chromium-review.googlesource.com/618892
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#47410}

src/heap/spaces.cc

@@ -1750,7 +1750,9 @@ void PagedSpace::Verify(ObjectVisitor* visitor) {
     CHECK_LE(black_size, marking_state->live_bytes(page));
   }
   CHECK(allocation_pointer_found_in_space);
+#ifdef DEBUG
   VerifyCountersAfterSweeping();
+#endif
 }
 #endif  // VERIFY_HEAP