This reverts commit b45c74f0f2.
It broke the cursor in other games. Apparently those use cursor data
with premultiplied alpha, but with some pixels having r/g/b values
larger than the alpha value (which corresponds to original r/g/b
values > 1.0), triggering the workaround.
Seems the cure turned out worse than the disease, so revert.
Bugzilla: https://bugs.freedesktop.org/108650