Disable subnormal floats on GL renderer filters and bg filters

This prevents timing attacks using SVG filters

Bug: 686253
Cq-Include-Trybots: master.tryserver.blink:linux_trusty_blink_rel
Change-Id: I54534bf93c4dfe954f667e5c210aa83d5c9abcf4
Reviewed-on: https://chromium-review.googlesource.com/552957
Commit-Queue: Fernando Serboncini <fserb@chromium.org>
Reviewed-by: enne <enne@chromium.org>
Cr-Commit-Position: refs/heads/master@{#483116}
1 file changed