reduce SkDisplacementImageFilter size.      Saves ~8K on mac laptop          - remove templates     - check for 0 0r 0xFF in alpha          Before: (using modified bench w/o caching)            23/23  MB     2       134µs   151µs   146µs   156µs   6%      █▇▆▆▆▆▄▁▁▁      8888    displacement_full_large       23/23  MB     2       253µs   254µs   255µs   260µs   1%      █▄▄▅▂▁▂▁▁▁      8888    displacement_alpha_large       24/24  MB     1       410µs   410µs   415µs   445µs   3%      █▃▁▂▁▁▁▁▁▁      8888    displacement_zero_large       24/24  MB     151     840ns   841ns   853ns   938ns   4%      █▁▁▁▁▁▁▂▁▁      8888    displacement_full_small       24/24  MB     180     832ns   835ns   836ns   851ns   1%      █▂▁▂▂▁▂▂▂▂      8888    displacement_alpha_small       24/24  MB     9       60µs    60.9µs  69.9µs  101µs   19%     █▄▄▄▁▁▁▁▁▁      8888    displacement_zero_small          After:            23/23  MB     3       47.4µs  48µs    48.2µs  51.4µs  2%      █▂▂▃▃▁▁▁▂▁      8888    displacement_full_large       23/23  MB     2       140µs   141µs   145µs   166µs   7%      ▂▁▁▁▁▁▁▁▇█      8888    displacement_alpha_large       24/24  MB     2       189µs   196µs   197µs   225µs   5%      █▃▂▂▂▂▃▂▁▁      8888    displacement_zero_large       24/24  MB     134     588ns   594ns   597ns   616ns   1%      ▂▁▁█▂▆▂▂▃▄      8888    displacement_full_small       24/24  MB     168     590ns   592ns   592ns   599ns   0%      ▃▂▁▁▁▁▁█▂▂      8888    displacement_alpha_small       24/24  MB     9       8.39µs  8.41µs  8.42µs  8.53µs  0%      █▄▃▂▁▁▃▂▁▂      8888    displacement_zero_small
reduce SkDisplacementImageFilter size.
    
Saves ~8K on mac laptop
    
    - remove templates
    - check for 0 0r 0xFF in alpha
    
    Before: (using modified bench w/o caching)
    
      23/23  MB     2       134µs   151µs   146µs   156µs   6%      █▇▆▆▆▆▄▁▁▁      8888    displacement_full_large
      23/23  MB     2       253µs   254µs   255µs   260µs   1%      █▄▄▅▂▁▂▁▁▁      8888    displacement_alpha_large
      24/24  MB     1       410µs   410µs   415µs   445µs   3%      █▃▁▂▁▁▁▁▁▁      8888    displacement_zero_large
      24/24  MB     151     840ns   841ns   853ns   938ns   4%      █▁▁▁▁▁▁▂▁▁      8888    displacement_full_small
      24/24  MB     180     832ns   835ns   836ns   851ns   1%      █▂▁▂▂▁▂▂▂▂      8888    displacement_alpha_small
      24/24  MB     9       60µs    60.9µs  69.9µs  101µs   19%     █▄▄▄▁▁▁▁▁▁      8888    displacement_zero_small
    
    After:
    
      23/23  MB     3       47.4µs  48µs    48.2µs  51.4µs  2%      █▂▂▃▃▁▁▁▂▁      8888    displacement_full_large
      23/23  MB     2       140µs   141µs   145µs   166µs   7%      ▂▁▁▁▁▁▁▁▇█      8888    displacement_alpha_large
      24/24  MB     2       189µs   196µs   197µs   225µs   5%      █▃▂▂▂▂▃▂▁▁      8888    displacement_zero_large
      24/24  MB     134     588ns   594ns   597ns   616ns   1%      ▂▁▁█▂▆▂▂▃▄      8888    displacement_full_small
      24/24  MB     168     590ns   592ns   592ns   599ns   0%      ▃▂▁▁▁▁▁█▂▂      8888    displacement_alpha_small
      24/24  MB     9       8.39µs  8.41µs  8.42µs  8.53µs  0%      █▄▃▂▁▁▃▂▁▂      8888    displacement_zero_small

This reverts commit 3f93b7265f558c414d0f33a7771be52b1fd1ce61.

fix: use PMColor shifts, not RGBA shifts

Bug: skia:
Change-Id: I044ef323b56d842f00cc50a828e14374aea8bb9e
Reviewed-on: https://skia-review.googlesource.com/20204
Commit-Queue: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>
Reviewed-by: Mike Reed <f5cabf8735907151a446812c9875d6c0c712d847@google.com>

HalCanary/skia-hc,google/skia,google/skia,HalCanary/skia-hc,google/skia,Hikari-no-Tenshi/android_external_skia,google/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,HalCanary/skia-hc,aosp-mirror/platform_external_skia,rubenvb/skia,aosp-mirror/platform_external_skia,rubenvb/skia,google/skia,Hikari-no-Tenshi/android_external_skia,rubenvb/skia,rubenvb/skia,HalCanary/skia-hc,rubenvb/skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,HalCanary/skia-hc,HalCanary/skia-hc,aosp-mirror/platform_external_skia,Hikari-no-Tenshi/android_external_skia,aosp-mirror/platform_external_skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,aosp-mirror/platform_external_skia,HalCanary/skia-hc,google/skia,rubenvb/skia,Hikari-no-Tenshi/android_external_skia,HalCanary/skia-hc,google/skia,google/skia,rubenvb/skia,aosp-mirror/platform_external_skia,google/skia,Hikari-no-Tenshi/android_external_skia