DevTools: handle gesture tap event while in inspecting element mode.

BUG=272109
TBR=vsevik

Review URL: https://chromiumcodereview.appspot.com/23085004

git-svn-id: svn://svn.chromium.org/blink/trunk@156039 bbb929c8-8fbe-4397-9dbb-9b2b20218538