Revert of Move the FontFaceCache stored in CSSFontSelector to be stored in Document. (patchset #5 id:80001 of https://codereview.chromium.org/2624893003/ )

Reason for revert:
Reverted on suspicion of causing the top renderer crash on Mac.

https://bugs.chromium.org/p/chromium/issues/detail?id=696231

Original issue's description:
> Move the FontFaceCache stored in CSSFontSelector to be stored in Document.
>
> This addresses a FIXME found in the code. This FIXME was added in
> 2013 by dglazkov in 2013, ad02388f5fcffaab45b9ada7a7dfdcae13ed460f.
>
> BUG=685945
>
> Review-Url: https://codereview.chromium.org/2624893003
> Cr-Commit-Position: refs/heads/master@{#452734}
> Committed: https://chromium.googlesource.com/chromium/src/+/e07e958d62db5bb606c0dbbb446d2a25e33c3db1

TBR=drott@chromium.org,eae@chromium.org,sashab@chromium.org,meade@chromium.org
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=685945

Review-Url: https://codereview.chromium.org/2728513002
Cr-Commit-Position: refs/heads/master@{#453842}
8 files changed