These aren't optional in SVG files. Browsers will display them without,
but dropping them breaks MIME type detection, which breaks data URI
embedding: the underline-u icon was being embedded as data:text/plain,...
Bug: 58119
Change-Id: Ia790877fcd536f2714626ccf47beadd09cb4fac9
Trevor tweaked the pixel grid snapping on my previous commit
but it appears that introduced some errors as well. The horizontal
lines in underline-a and strikethrough-s no longer have integer
x-coordinates, and on underline-u the whole object is offset
by (0.166, 0.166).
Bug: 47780
Change-Id: I51f2605e7d8e2bab1d641f02244d5cd24f505676