Enable NV_path_rendering in the Null GL.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1882563002

Review URL: https://codereview.chromium.org/1882563002
diff --git a/tools/gpu/GrContextFactory.cpp b/tools/gpu/GrContextFactory.cpp
index 651f3fc..eb0f414 100755
--- a/tools/gpu/GrContextFactory.cpp
+++ b/tools/gpu/GrContextFactory.cpp
@@ -141,7 +141,7 @@
                     break;
 #endif
                 case kNullGL_ContextType:
-                    glCtx.reset(CreateNullGLTestContext());
+                    glCtx.reset(CreateNullGLTestContext(kEnableNVPR_ContextOptions & options));
                     break;
                 case kDebugGL_ContextType:
                     glCtx.reset(CreateDebugGLTestContext());