XPath: Apply ASCII-case-insensitive matching to HTML elements

HTML element names usually compared with ASCII case-insensitive way,
not Unicode caseless way though we didn't find any standards defining
this behavior in XPath.
The new behavior matches to Firefox and Safari.

Bug: 627682
Change-Id: I4c7a86dbd5aa9661df28571585fbb68aa2e6b6a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578721
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Kent Tamura <tkent@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653459}
2 files changed