Revert "Improvements to GPU dither."

This reverts commit 1806e33e6a09b1361de4925d32389a01e0e2c7e7.

Reason for revert: <INSERT REASONING HERE>

Original change's description:
> Improvements to GPU dither.
> 
> 1) Makes the range of the offset dependent on the config.
> 
> 2) Uses an ordered dither on GPUs that support integers in shaders.
> 
> 3) Enables dithering for all paints with dither flag when the color type of the dst is 4444
> 
> 4) Dithers r,g,b and clamps to 0,a rather than dithering all four channels (same as CPU backend).
> 
> Bug: skia:
> Change-Id: Ie22c3adc38c6d1dbbcd97e4b7d16fc843e392c2e
> Reviewed-on: https://skia-review.googlesource.com/23485
> Commit-Queue: Brian Salomon <bsalomon@google.com>
> Reviewed-by: Robert Phillips <robertphillips@google.com>

TBR=bsalomon@google.com,robertphillips@google.com

Change-Id: Ie82e88bd9032bf8eee745d32d9b57c335a8997c9
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/24325
Reviewed-by: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Salomon <bsalomon@google.com>

1 files changed, 2 insertions, 2 deletions

diff --git a/src/core/SkPaintPriv.cpp b/src/core/SkPaintPriv.cpp
index 7d771f88a6..dcd8dd6a5a 100644
--- a/src/core/SkPaintPriv.cpp
+++ b/src/core/SkPaintPriv.cpp
@@ -75,8 +75,8 @@ bool SkPaintPriv::ShouldDither(const SkPaint& p, SkColorType dstCT) {
         return false;
     }
 
-    // We always dither 565 or 4444 when requested.
-    if (dstCT == kRGB_565_SkColorType || dstCT == kARGB_4444_SkColorType) {
+    // We always dither 565 when requested.
+    if (dstCT == SkColorType::kRGB_565_SkColorType) {
         return true;
     }