DevTools: [Elements] fix editing as HTML inplace editor scrolling

The patch prevents ElementTreeELements from selecting if they have
inner inplace editor.

BUG=423720

Review URL: https://codereview.chromium.org/663453003

git-svn-id: svn://svn.chromium.org/blink/trunk@183809 bbb929c8-8fbe-4397-9dbb-9b2b20218538