Issue #1529814 by mgifford, JohnAlbin, ibullock, dcmouyard, mark.labrecque, andrewmacpherson, vegantriathlete: Fixed skiplink behavior for Webkit browsers.

Issue #2052473 by ricky.middaugh, lokapujya, Jalandhar, mgifford, jessebeach, BarisW, falcon03: Add aria-label or aria-describedby attributes to all <nav> elements.

Issue #1880488 by djroshi, konstantin.komelin, LewisNyman, jibran, rteijeiro: Added Make menu collapsible on small screen resolutions.

Issue #2226185 by galooph, filijonka, Cottser: Remove @ingroup themeable from core theme Twig template docblocks.

Issue #1843650 by Mark Carver, jenlampton, Cottser: Remove the process layer (hook_process() and hook_process_HOOK).

Issue #1589968 by cr0ss, Cottser, Pancho, DarthDrupal, Mark Carver: Move Title from process to preprocess, remove template_process_page().

Issue #2013094 by pwieck, Cottser: Remove unnecessary template_preprocess() reference from all Twig files

Issue #1363112 by mparker17, mgifford, tlattimore, Jacine, dcmouyard, bowersox, ry5n, ahdiaz: Simplify names of 'element-x' helper classes.

Issue #1961870 by Cottser, foopang, kgoel, shanethehat, tlattimore, c4rl, joelpittet, thedavidmeister: Convert page.tpl.php to Twig.