[in-place weak refs] Fix: MarkCompactCollector::AbortWeakObjects must clear weak references.

BUG=v8:7308

Change-Id: I0e029bcc157a0e62bf7aa2d222118003a29b4436
Reviewed-on: https://chromium-review.googlesource.com/952443Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51780}

src/heap/mark-compact.cc

@@ -2932,6 +2932,7 @@ void MarkCompactCollector::ClearWeakReferences() {
 void MarkCompactCollector::AbortWeakObjects() {
   weak_objects_.weak_cells.Clear();
   weak_objects_.transition_arrays.Clear();
+  weak_objects_.weak_references.Clear();
 }
 
 void MarkCompactCollector::RecordRelocSlot(Code* host, RelocInfo* rinfo,