Make GrDrawTarget::Caps ref counted and GrGLCaps derive from it.

src/gpu/GrGpu.cpp

Index: src/gpu/GrGpu.cpp
===================================================================
--- src/gpu/GrGpu.cpp	(revision 8359)
+++ src/gpu/GrGpu.cpp	(working copy)
@@ -204,7 +204,7 @@
 }
 
 GrPath* GrGpu::createPath(const SkPath& path) {
-    GrAssert(fCaps.pathStencilingSupport());
+    GrAssert(this->caps()->pathStencilingSupport());
     this->handleDirtyContext();
     return this->onCreatePath(path);
 }