Bug 1679700 - Cast int parameter in get_yuv_offset_vector to float, to work around a shader compilation bug with integer equality comparisons on macOS Intel. r=jrmuizel
Bug 1679700 - Cast int parameter in get_yuv_offset_vector to float, to work around a shader compilation bug with integer equality comparisons on macOS Intel. r=jrmuizel

We've encountered similar bugs before, e.g.
https://github.com/servo/webrender/wiki/Driver-issues#3540---mac-glsl-compiler-bug-with-integer-comparison-take-two

We don't want to change this `if` to a `switch` because glsl-opt compiles it
down to an if statement anyway, just a more complicated one (which was triggering
other bugs on other platforms, see bug 1678924).

Differential Revision: https://phabricator.services.mozilla.com/D98208

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/5d4b227d3b5c5ff38ffc012a9ce792e28fc51958

servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender,servo/webrender