[heap] Fix uninitialized value in GCTracer

Tbr: ulan@chromium.org
Bug: chromium:948807, chromium:978050
Change-Id: I73d4ca4ca43b9c9bfa57502676bab9f60b052229
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1674036
Commit-Queue: Michael Lippautz <mlippautz@chromium.org>
Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Michael Lippautz <mlippautz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#62343}

src/heap/gc-tracer.cc

@@ -150,9 +150,11 @@ GCTracer::GCTracer(Heap* heap)
       allocation_time_ms_(0.0),
       new_space_allocation_counter_bytes_(0),
       old_generation_allocation_counter_bytes_(0),
+      embedder_allocation_counter_bytes_(0),
       allocation_duration_since_gc_(0.0),
       new_space_allocation_in_bytes_since_gc_(0),
       old_generation_allocation_in_bytes_since_gc_(0),
+      embedder_allocation_in_bytes_since_gc_(0),
       combined_mark_compact_speed_cache_(0.0),
       start_counter_(0),
       average_mutator_duration_(0),