added support for PLS path rendering

src/gpu/GrGpu.cpp

Index: src/gpu/GrGpu.cpp
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index 2815f612d602707c2186d1348d8deca5ba45c426..4079829f00d3cabbf40a7be0ec2688c08bfb0f14 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -367,6 +367,9 @@ void GrGpu::resolveRenderTarget(GrRenderTarget* target) {
     this->onResolveRenderTarget(target);
 }
 
+void GrGpu::performFlushWorkaround() {
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void GrGpu::draw(const DrawArgs& args, const GrVertices& vertices) {
@@ -382,3 +385,4 @@ void GrGpu::draw(const DrawArgs& args, const GrVertices& vertices) {
         fStats.incNumDraws();
     } while ((verts = iter.next()));
 }
+