16433 Various fixes in CanvasKit (cla: yes)

16434 Fix RasterCache LRU logic + opportunistic simplifications. (cla: yes)

16440 fix bad reference to maxDiffRatePercent (cla: yes)

16442 Include  in hb_wrapper.h because unique_ptr is used. (cla: yes)

16446 Relax timing restrictions on WakeUpTimersAreSingletons. (cla: yes)

16450 Gather demangled stack traces and report the same to console on crashes. (cla: yes, waiting for tree to go green)

16454 Roll fuchsia/sdk/core/mac-amd64 from ubThi… to fvWgE… (autoroller: commit, cla: yes)