Crop the fast path dashed lines to the cull rect

Without:

maxrss  loops   min     median  mean    max     stddev  samples         config  bench
  56M   1       13.3ms  13.6ms  13.6ms  14.2ms  2%      Ooooo.....      8888    GM_dashing5_bw
  56M   13      390us   417us   416us   459us   5%      ooooO..o.o      gpu     GM_dashing5_bw
  56M   1       13.4ms  13.9ms  14.1ms  15ms    3%      Oooo..ooOo      8888    GM_dashing5_aa
  56M   13      402us   421us   416us   425us   2%      Ooo.ooOOOO      gpu     GM_dashing5_aa

With:

  40M   1       1.53ms  1.54ms  1.54ms  1.55ms  0%      oo.O...o..      8888    GM_dashing5_bw
  40M   12      407us   412us   415us   445us   3%      ...Oo.....      gpu     GM_dashing5_bw
  40M   1       1.7ms   1.7ms   1.7ms   1.72ms  0%      o.O.......      8888    GM_dashing5_aa
  43M   13      405us   409us   409us   415us   1%      ooo.Ooo..o      gpu     GM_dashing5_aa

The GM images (including the new one) are the same with and without this CL.

BUG=428296

Review URL: https://codereview.chromium.org/699623003
5 files changed