Eradicate keyIndentifier from devtools/*

keyIdentifier is going to be deprecated; we need to stop using it.

No functional changes intended. A few instances remain with respect
to extensions and keyIdentifier. Those need to be handled so that
we don't break existing extensions.

BUG=607349

Review-Url: https://codereview.chromium.org/2033403005
Cr-Commit-Position: refs/heads/master@{#401423}
36 files changed