DevTools: remove the 'always allow' self-xss dialog. It is likely to be replaced with the different first-run experience.

BUG=345205
TBR=vsevik

Review URL: https://codereview.chromium.org/263833015

git-svn-id: svn://svn.chromium.org/blink/trunk@173365 bbb929c8-8fbe-4397-9dbb-9b2b20218538