Web MIDI: allow http://localhost to prompt sysex permission

Allow to obtain a sysex permission for localhost even if the scheme is
non-secure. This is inteded for to use for testing.

TEST=manual check with http://localhost:xxx and http://127.0.0.1:xxx
BUG=470170

Review URL: https://codereview.chromium.org/1050063002

Cr-Commit-Position: refs/heads/master@{#323555}
1 file changed