Remove SimpleFontData::create only used by SVG Fonts

SVG Fonts were removed in:
https://codereview.chromium.org/656913006

That removed the last caller to SimpleFontData::create.

Review URL: https://codereview.chromium.org/682793002

git-svn-id: svn://svn.chromium.org/blink/trunk@184486 bbb929c8-8fbe-4397-9dbb-9b2b20218538