Revert "Reland "Use new Skia GPU read/write pixel code paths""

This reverts commit 613f5543.

Reason for revert: 
Breaks fast/webgl/canvas-toDataURL-premul-overflow.html on
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty/43191
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty%20Leak/17758
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Linux%20Trusty%20(dbg)/11632
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Mac10.10/45887
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Mac10.11/31889
https://ci.chromium.org/buildbot/chromium.webkit/WebKit%20Mac10.12%20(retina)/328

Original change's description:
> Reland "Use new Skia GPU read/write pixel code paths"
> 
> This reverts commit 56044665.
> 
> Reason for revert: Fast paths for premul/unpremul RGBA added to new code paths to accelerate get/putImageData.
> 
> Original change's description:
> > Revert "Use new Skia GPU read/write pixel code paths"
> > 
> > This reverts commit f17c70fe.
> > 
> > Reason for revert: 
> > 
> > It looks like this change:
> > 
> > slowed down the file___static_top_25_weather.html rasterize_and_record time on the AndroidOne (crbug.com/825594)
> > 
> > slowed down getImageData and putImageData for the HTML5 Canvas across the board (crbug.com/825585)
> > 
> > Bug: 825594
> > Bug: 825585
> > 
> > Original change's description:
> > > Use new Skia GPU read/write pixel code paths
> > > 
> > > Change-Id: I8ea66d1b3bb8db174deab690a0cdacc39cf81992
> > > Reviewed-on: https://chromium-review.googlesource.com/973267
> > > Reviewed-by: Robert Phillips <robertphillips@google.com>
> > > Commit-Queue: Brian Salomon <bsalomon@chromium.org>
> > > Cr-Commit-Position: refs/heads/master@{#544777}
> > 
> > TBR=bsalomon@chromium.org,robertphillips@google.com
> > 
> > # Not skipping CQ checks because original CL landed > 1 day ago.
> > 
> > Change-Id: Icaee5a1afa55bc8aec4567687661dacef0ccf565
> > Reviewed-on: https://chromium-review.googlesource.com/980292
> > Reviewed-by: Robert Phillips <robertphillips@google.com>
> > Commit-Queue: Robert Phillips <robertphillips@google.com>
> > Cr-Commit-Position: refs/heads/master@{#545787}
> 
> TBR=bsalomon@chromium.org,robertphillips@google.com
> 










> # Not skipping CQ checks because original CL landed > 1 day ago.
> 
> Bug: 825594, 825585
> Change-Id: I82434eebb65257cf6a92225c2c862fe22aecf093
> Reviewed-on: https://chromium-review.googlesource.com/1014140
> Reviewed-by: Brian Salomon <bsalomon@chromium.org>
> Reviewed-by: Robert Phillips <robertphillips@google.com>
> Commit-Queue: Brian Salomon <bsalomon@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#551022}

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

Change-Id: I0dd6db48f1c55d869de88e2fbca963c2c0cde0ab
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 825594, 825585
Reviewed-on: https://chromium-review.googlesource.com/1012796Reviewed-by: Justin Novosad <junov@chromium.org>
Commit-Queue: Justin Novosad <junov@chromium.org>
Cr-Commit-Position: refs/heads/master@{#551093}

skia/config/SkUserConfig.h

@@ -208,6 +208,11 @@ SK_API void SkDebugf_FileLine(const char* file, int line, bool fatal,
 #define SK_SUPPORT_LEGACY_SVG_ARC_TO
 #endif
 
+// Remove after M66 branch to use new read/writePixels implementations
+#ifndef SK_LEGACY_GPU_PIXEL_OPS
+#define SK_LEGACY_GPU_PIXEL_OPS
+#endif
+
 #ifndef SK_SUPPORT_LEGACY_YUV_COLORSPACE
 #define SK_SUPPORT_LEGACY_YUV_COLORSPACE
 #endif