[DevTools] Make sure ZoomManager captures resize event first.

If it doesn't, any code running in onresize handler may have
a wrong idea of current zoom and misbehave.

BUG=397962

Review URL: https://codereview.chromium.org/429923003

git-svn-id: svn://svn.chromium.org/blink/trunk@179391 bbb929c8-8fbe-4397-9dbb-9b2b20218538