Use a single stencil buffer for a given width,height,samplecount

Review URL: http://codereview.appspot.com/4854044/


git-svn-id: http://skia.googlecode.com/svn/trunk@2061 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/gpu/src/GrGLRenderTarget.cpp b/gpu/src/GrGLRenderTarget.cpp
index 39aa332..ccfc55a 100644
--- a/gpu/src/GrGLRenderTarget.cpp
+++ b/gpu/src/GrGLRenderTarget.cpp
@@ -78,7 +78,7 @@
     fMSColorRenderbufferID  = 0;
     GrSafeUnref(fTexIDObj);
     fTexIDObj = NULL;
-    GrSafeSetNull(fStencilBuffer);
+    this->setStencilBuffer(NULL);
 }
 
 void GrGLRenderTarget::onAbandon() {
@@ -89,6 +89,6 @@
         fTexIDObj->abandon();
         fTexIDObj = NULL;
     }
-    GrSafeSetNull(fStencilBuffer);
+    this->setStencilBuffer(NULL);
 }