DevTools: disable filters bar when switching Timeline to flame chart mode

The filters status bar button gets disabled and the filters bar is hidden.

BUG=None

Review URL: https://codereview.chromium.org/713483002

git-svn-id: svn://svn.chromium.org/blink/trunk@184974 bbb929c8-8fbe-4397-9dbb-9b2b20218538