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 e2457ce31e4f47325e81ba1c3f744678e1399c24..99e92c0ef07c5c53c4f52405172e2545a21ee548 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -352,6 +352,9 @@ void GrGpu::resolveRenderTarget(GrRenderTarget* target) {
     this->onResolveRenderTarget(target);
 }
 
+void GrGpu::performFlushWorkaround() {
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 
 void GrGpu::draw(const DrawArgs& args, const GrVertices& vertices) {
@@ -367,3 +370,4 @@ void GrGpu::draw(const DrawArgs& args, const GrVertices& vertices) {
         fStats.incNumDraws();
     } while ((verts = iter.next()));
 }
+