switched gl_Position and gl_PointSize to sk_*

Bug: skia:
Change-Id: Ie7508991aa975c1400bac23ae49d81041a313968
Reviewed-on: https://skia-review.googlesource.com/51320
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Ethan Nicholas <ethannicholas@google.com>
diff --git a/src/gpu/ccpr/GrCCPRCoverageProcessor.cpp b/src/gpu/ccpr/GrCCPRCoverageProcessor.cpp
index a295f05..4a0dd26 100644
--- a/src/gpu/ccpr/GrCCPRCoverageProcessor.cpp
+++ b/src/gpu/ccpr/GrCCPRCoverageProcessor.cpp
@@ -145,7 +145,7 @@
             fnBody.appendf("%s = %s * %s;",
                            fFragCoverageTimesWind.gsOut(), coverage, fGeomWind.c_str());
         }
-        fnBody.append ("gl_Position = float4(position, 0, 1);");
+        fnBody.append ("sk_Position = float4(position, 0, 1);");
         fnBody.append ("EmitVertex();");
         return fnBody;
     }().c_str(), &emitVertexFn);