Revert of Move HTMLDocument::isCaseSensitiveAttribute into SelectorChecker (patchset #1 id:1 of https://codereview.chromium.org/2313253002/ )

Reason for revert:
Possible cause of regression in blink_perf.parser.

BUG=645370

Original issue's description:
> Move HTMLDocument::isCaseSensitiveAttribute into SelectorChecker
>
> BUG=238368
> R=esprehn@chromium.org,rune@opera.com
>
> Committed: https://crrev.com/e912108e9daf83d1bec61e5b78aaacf965a3e2fc
> Cr-Commit-Position: refs/heads/master@{#416903}

TBR=esprehn@chromium.org,rune@opera.com
# Not skipping CQ checks because original CL landed more than 1 days ago.
BUG=238368

Review-Url: https://codereview.chromium.org/2326493004
Cr-Commit-Position: refs/heads/master@{#417571}
3 files changed