Usage of DirectWrite now determined browser-side

Enabling DirectWrite requires the sandbox to have knowledge of whether
DirectWrite or GDI is used for font rendering, so it's now decided
in the browser. Don't do fallback behavior in the renderer any more.

Browser side is https://codereview.chromium.org/209163002/ .

R=jamesr@chromium.org
BUG=333029

Review URL: https://codereview.chromium.org/210243004

git-svn-id: svn://svn.chromium.org/blink/trunk@170075 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Mark device-emulation-scale-only as failing on Mac

TBR=dgozman
BUG=356743

Review URL: https://codereview.chromium.org/212883003

git-svn-id: svn://svn.chromium.org/blink/trunk@170076 bbb929c8-8fbe-4397-9dbb-9b2b20218538