Summary: 'font-synthesis: small-caps' allows the UA to synthesize
a small-caps variant when this is not supported by a font face.
We have done this by default until now, so the new feature is that
you can now turn that off with a 'font-synthesis' value that
excludes the 'small-caps' keyword.
Platform coverage: all
Other browsers: Safari supports 'font-synthesis: small-caps'.
Chrome doesn't seem to support the 'font-synthesis' property
Web Platform Tests: added in the patch