Unifying XML declaration for markup parity and to align to SVG coding
conventions.
Also manually optimizing several others.
Change-Id: I5dc71dc3cea6dde054d3e60ca3337e20ed661568
The previous lot of link icons look great on high DPI displays but not
as nice as they could on standard resolution displays. According to
Volker, this is because the SVG paths must appear on integer coordinates
and scale up instead of down. The new assets have been designed with
this consideration in mind.
Also, workaround redundant CSS by adding commenting out the "unvaried"
black SVG background-image selector, selectorWithoutVariant.
Bug: T190549
Bug: T197909
Change-Id: Id341d383018a436401541e82cc75d826688eaaae