Initial support for GL_NV_path_renering. Experimental, there are still some issues to resolve, set gyp variable skia_nv_path_rendering=1 or build flag GR_GL_USE_NV_PATH_RENDERING to enable.

http://codereview.appspot.com/6349049/



git-svn-id: http://skia.googlecode.com/svn/trunk@4390 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrDrawTarget.cpp b/src/gpu/GrDrawTarget.cpp
index 64dc815..745e4c9 100644
--- a/src/gpu/GrDrawTarget.cpp
+++ b/src/gpu/GrDrawTarget.cpp
@@ -818,8 +818,9 @@
     }
 }
 
-void GrDrawTarget::stencilPath(const GrPath& path, GrPathFill fill) {
+void GrDrawTarget::stencilPath(const GrPath* path, GrPathFill fill) {
     // TODO: extract portions of checkDraw that are relevant to path stenciling.
+    GrAssert(NULL != path);
     GrAssert(fCaps.fPathStencilingSupport);
     GrAssert(kHairLine_GrPathFill != fill);
     GrAssert(!GrIsFillInverted(fill));