Use last value for axis for variation position.

SkFontArguments::VariationPosition may be over specified. If there are
multiple values for a given axis, ensure the last value specified is
used, since that's what css-fonts-4 requires.

BUG=chromium:674878

Change-Id: I6704c15c520c89efb9ee84659a3e16e0d07691c9
Reviewed-on: https://skia-review.googlesource.com/10513
Commit-Queue: Mike Klein <mtklein@chromium.org>
Reviewed-by: Mike Klein <mtklein@chromium.org>
3 files changed