DevTools: fix overrides dirty marker wrt emulateResolution bit.

TBR=dgozman
NOTRY=true

Review URL: https://codereview.chromium.org/347373002

git-svn-id: svn://svn.chromium.org/blink/trunk@176721 bbb929c8-8fbe-4397-9dbb-9b2b20218538