Our gfxPattern cache is currently way too specific, which causes lots of
unnecessary cache misses. The only thing that we actually need to key on is the
color stops.
This switches the cache to hold GradientStops instead of gfxPatterns. This
improves our cache hit rate and is simpler. It also avoids doing caching when
not using Azure, which currently has no benefit.
Average paint times results (in ms)
(on windows 7 x64, i7-3630qm, HD4000)
-------------------------------------
m-c
open: 3.5 close: 3.3
m-c cache-key
open: 2.6 close: 2.4
ux
open: 7.3 close: 5.2
ux cache-key
open: 6.9 close: 5.3
8ba2f637aa