Revert "Drop support for unused MSAA extensions"

This reverts commit 7df27465c4ecc8a4a0cdd95e9785c342903c2de9.

Reason for revert: experimental revert to see if this is the cause of the tree redness

Original change's description:
> Drop support for unused MSAA extensions
> 
> Bug: skia:
> Change-Id: I113b80e3f991f195155148625ceb29242ea82776
> Reviewed-on: https://skia-review.googlesource.com/101403
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Chris Dalton <csmartdalton@google.com>

TBR=bsalomon@google.com,csmartdalton@google.com,ethannicholas@google.com

Change-Id: I4fa4123e2d176bef88cd76a09a14053d9ac5809f
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: skia:
Reviewed-on: https://skia-review.googlesource.com/101680
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
diff --git a/src/gpu/effects/GrBitmapTextGeoProc.cpp b/src/gpu/effects/GrBitmapTextGeoProc.cpp
index 3d822e0..a9ebdca 100644
--- a/src/gpu/effects/GrBitmapTextGeoProc.cpp
+++ b/src/gpu/effects/GrBitmapTextGeoProc.cpp
@@ -43,7 +43,7 @@
         append_index_uv_varyings(args, btgp.inTextureCoords()->fName, atlasSizeInvName,
                                  &uv, &texIdx, nullptr);
 
-        GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
+        GrGLSLPPFragmentBuilder* fragBuilder = args.fFragBuilder;
         // Setup pass through color
         if (btgp.hasVertexColor()) {
             varyingHandler->addPassThroughAttribute(btgp.inColor(), args.fOutputColor);