- Revert "[builtins] Save one word in contexts for Promise.all."
  This reverts commit 7632da06.
- Revert "[builtins] Also use the Promise#then protector for Promise#finally()."
  This reverts commit d4f072ce.
- Revert "[builtins] Don't mess with entered context for MicrotaskCallbacks."
  This reverts commit 6703dacd.
- Revert "[debugger] Properly deal with settled promises in catch prediction."
  This reverts commit 40dd0658.
- Revert "[builtins] Widen the fast-path for Promise builtins."
  This reverts commit db0556b7.
- Revert "[builtins] Unify PerformPromiseThen and optimize it with TurboFan."
  This reverts commit a582199c.
- Revert "[builtins] Remove obsolete PromiseBuiltinsAssembler::AppendPromiseCallback."
  This reverts commit 6bf88852.
- Revert "[builtins] Turn NewPromiseCapability into a proper builtin."
  This reverts commit 313b490d.
- Revert "[builtins] Inline InternalPromiseThen into it's only caller"
  This reverts commit f7bd6a2f.
- Revert "[builtins] Implement Promise#catch by really calling into Promise#then."
  This reverts commit b23b098f.
- Revert "[promise] Remove incorrect fast path"
  This reverts commit 0f6eafe8.
- Revert "[builtins] Squeeze JSPromise::result and JSPromise::reactions into a single field."
  This reverts commit 8a677a28.
- Revert "[builtins] Refactor promises to reduce GC overhead."
  This reverts commit 8e7737cb.

Tbr: hpayer@chromium.org
Bug: chromium:800651, chromium:808911, v8:5691, v8:7253
Change-Id: I8c8ea5ed32ed62f6cd8b0d027a3707ddd891e5f1
Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Reviewed-on: https://chromium-review.googlesource.com/906991
Commit-Queue: Yang Guo <yangguo@chromium.org>
Commit-Queue: Adam Klein <adamk@chromium.org>
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Benedikt Meurer <bmeurer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51158}