Remove x-webkit-speech and x-webkit-grammar from HTMLAttributeNames.in

These are no longer used.

BUG=none

Review URL: https://codereview.chromium.org/290593002

git-svn-id: svn://svn.chromium.org/blink/trunk@174144 bbb929c8-8fbe-4397-9dbb-9b2b20218538