Remove wtf::String::characterAt.

This was done for some vague compiler reason in webkit,
but is not really used by Blink and there's no do mention
in the original bug https://bugs.webkit.org/show_bug.cgi?id=95509

Lets just remove it.

Review-Url: https://codereview.chromium.org/2026103002
Cr-Commit-Position: refs/heads/master@{#396992}
2 files changed