Remove isindex parsing special case #1088
Description
Blink and EdgeHTML no longer implement special-case parsing for isindex.
Blink, at least, per https://codereview.chromium.org/96653004/, also removed the special support for first-in-form text controls named "isindex". I haven't tested Edge on that.
We should consider removing it, if at least one of Gecko and WebKit is interested in doing so. I'll file bugs:
- Gecko bug: https://bugzilla.mozilla.org/show_bug.cgi?id=1266495
- WebKit bug: https://bugs.webkit.org/show_bug.cgi?id=7139