Update the mobile page menu and header to work with page themes.
Review Request #7244 — Created April 23, 2015 and submitted
The header and slide-out menu now match the page's theme, providing a consistent look on smaller devices. This works for all pages that provide such a menu. I've also fixed showing the page mask on the dashboard, fixed the z-indexes for the mobile menu and mask, and added a transition when showing/hiding the mask.
Tested the dashboard, review request, and administration pages in a mobile
mode. They all looked as expected (aside from the administration page, which
has some existing visual quirks apparently unrelated to this work).