Use noperspective interpolation for 2D draws

src/gpu/GrPathProcessor.cpp

Index: src/gpu/GrPathProcessor.cpp
diff --git a/src/gpu/GrPathProcessor.cpp b/src/gpu/GrPathProcessor.cpp
index cb33010f7e7dec60e685a184169dcaca72d34ff5..1d70dea289548612dbbecf56596f5e74ac9205ad 100644
--- a/src/gpu/GrPathProcessor.cpp
+++ b/src/gpu/GrPathProcessor.cpp
@@ -22,13 +22,18 @@ public:
                        const GrGLSLCaps&,
                        GrProcessorKeyBuilder* b) {
         b->add32(SkToInt(pathProc.overrides().readsColor()) |
-                 SkToInt(pathProc.overrides().readsCoverage()) << 16);
+                 (SkToInt(pathProc.overrides().readsCoverage()) << 1) |
+                 (SkToInt(pathProc.viewMatrix().hasPerspective()) << 2));
     }
 
     void emitCode(EmitArgs& args) override {
         GrGLSLFragmentBuilder* fragBuilder = args.fFragBuilder;
         const GrPathProcessor& pathProc = args.fGP.cast<GrPathProcessor>();
 
+        if (!pathProc.viewMatrix().hasPerspective()) {
+            args.fVaryingHandler->setNoPerspective();
+        }
+
         // emit transforms
         this->emitTransforms(args.fVaryingHandler, args.fTransformsIn, args.fTransformsOut);