GitLab

This removes
- V8MemoryReducerForSmallHeaps
- V8HugeMaxOldGenerationSize
- kV8GCBackgroundSchedule
- kV8GCLessCompaction
- kV8GCAlwaysPromoteYoungMC

Bug: 933107,958974,966832,1014943
Change-Id: Id7bebc72a0c8c6ecbb0ef2eb44339a0dcfbb5a4b
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2089758Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747627}