Revert of Disable support for swapped out RenderFrame(Host) (patchset #2 id:20001 of https://codereview.chromium.org/1409773004/ )

Reason for revert:
More bugs got exposed:

https://crbug.com/543896
https://crbug.com/544755
https://crbug.com/544868

Original issue's description:
> Disable support for swapped out RenderFrame(Host)
>
> Attempt at disabling swapped out RenderFrame(Host) usage. Bugs fixed
> since last attempt:
>
> https://crbug.com/541578
> https://crbug.com/543226
> https://crbug.com/544271
>
> BUG=357747
>
> Committed: https://crrev.com/0b480ba36c61900d2941897bc74f42c8e70fd5cd
> Cr-Commit-Position: refs/heads/master@{#354663}

TBR=creis@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=357747

Review URL: https://codereview.chromium.org/1409373006

Cr-Commit-Position: refs/heads/master@{#354857}
1 file changed