Conditionally insert gl_PointSize into shaders.

BUG=chromium:648816
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2358843002

Review-Url: https://codereview.chromium.org/2358843002
diff --git a/src/gpu/instanced/GLInstancedRendering.cpp b/src/gpu/instanced/GLInstancedRendering.cpp
index bd014ec..dabfe4e 100644
--- a/src/gpu/instanced/GLInstancedRendering.cpp
+++ b/src/gpu/instanced/GLInstancedRendering.cpp
@@ -204,7 +204,7 @@
     if (!fDrawIndirectBuffer && !fGLDrawCmdsInfo) {
         return; // beginFlush was not successful.
     }
-    if (!this->glGpu()->flushGLState(pipeline, instProc)) {
+    if (!this->glGpu()->flushGLState(pipeline, instProc, false)) {
         return;
     }