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

Also rename GrDrawTarget::getCaps() -> GrDrawTarget::caps().
Review URL: https://codereview.chromium.org/12843026

git-svn-id: http://skia.googlecode.com/svn/trunk@8364 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/GrGpu.cpp b/src/gpu/GrGpu.cpp
index b5cdc5c..ba7bedd 100644
--- a/src/gpu/GrGpu.cpp
+++ b/src/gpu/GrGpu.cpp
@@ -204,7 +204,7 @@
 }
 
 GrPath* GrGpu::createPath(const SkPath& path) {
-    GrAssert(fCaps.pathStencilingSupport());
+    GrAssert(this->caps()->pathStencilingSupport());
     this->handleDirtyContext();
     return this->onCreatePath(path);
 }