Revert of Update test262-es6 to 6/11 (patchset #2 id:40001 of https://codereview.chromium.org/1175313003/)

Reason for revert:
[Sheriff] Please fix test expectations for nosnap before reland. There are 54 tests failing:
http://build.chromium.org/p/client.v8/builders/V8%20Linux%20-%20nosnap/builds/3422

Original issue's description:
> Update test262-es6 to 6/11
>
> This reverts commit 67b16919 and picks
> up the fixes to the yaml parser upstream.
>
> BUG=N
> LOG=N
> R=adamk@chromium.org, machenbach@chromium.org
>
> Committed: https://crrev.com/bc847230610d0518a700a69546d23784e6ce3479
> Cr-Commit-Position: refs/heads/master@{#29056}

TBR=adamk@chromium.org,arv@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=N

Review URL: https://codereview.chromium.org/1186093005

Cr-Commit-Position: refs/heads/master@{#29067}