Use removeFontFace to avoid resetting fontSelector.

BUG=305885
TEST=fast/css/font-face-remove.html, fast/css/font-face-html-as-svg.html

Review URL: https://codereview.chromium.org/82583005

git-svn-id: svn://svn.chromium.org/blink/trunk@164691 bbb929c8-8fbe-4397-9dbb-9b2b20218538