Bug 1688820 - force blend_pixels to inline more aggressively. r=jrmuizel
Bug 1688820 - force blend_pixels to inline more aggressively. r=jrmuizel

It appears that the slight refactoring of blend_pixels from the clip-mask
optimization in bug 1688104 caused clang-cl to inline blend_pixels more
pessimistically than it was doing before. Since this is an extremely hot
function that all alpha-pass rendering relies on, we generally just want
to inline this regardless of the slight increase in compile size since
a failure to aggressively optimize this can have noticeable performance
impacts.

Differential Revision: https://phabricator.services.mozilla.com/D103033

[ghsync] From https://hg.mozilla.org/mozilla-central/rev/28c7fb5899c41313eb70f182b53a0d04debcbf55

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