Floating point MQs should not match.

Floating point values inside MQs should not be round down/up
to match the integer dimensions of the viewport. That is in order to align our behavior with the way Gecko are doing that.
This CL fixes that issue.

BUG=422234

Review URL: https://codereview.chromium.org/644813005

git-svn-id: svn://svn.chromium.org/blink/trunk@183563 bbb929c8-8fbe-4397-9dbb-9b2b20218538