[heap] Fix threshold for delayed chunks after 2c7561.

Bug: chromium:771966
Change-Id: Iac5ee55c0d31de477f21f091f4be015a1ca8d00c
Reviewed-on: https://chromium-review.googlesource.com/702382Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#48316}

src/heap/heap.cc

@@ -1937,7 +1937,7 @@ void Heap::Scavenge() {
 
   if (mark_compact_collector()->sweeper().sweeping_in_progress() &&
       memory_allocator_->unmapper()->NumberOfDelayedChunks() >
-          kMaxSemiSpaceSizeInKB / Page::kPageSize) {
+          static_cast<int>(new_space_->MaximumCapacity() / Page::kPageSize)) {
     mark_compact_collector()->EnsureSweepingCompleted();
   }