In current implementation in expressions like await foo() we have break location right after foo call and before actual await.
And we additionally have a lot of other statement locations because of do scope.

Let's move async debugging closer to sync debugging and introduce only one break location for await - before awaited function call.

Bug: v8:6425,v8:6162
Change-Id: I7568767856022c49101e7f3b7e39a2e401d21644
Reviewed-on: https://chromium-review.googlesource.com/514046Reviewed-by: Marja Hölttä <marja@chromium.org>
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Aleksey Kozyatinskiy <kozyatinskiy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#45625}