My clang now doesn't complain about !"foo".

BUG=
R=robertphillips@google.com

Review URL: https://codereview.chromium.org/22875037

git-svn-id: http://skia.googlecode.com/svn/trunk@10874 2bbb7eff-a529-9590-31e7-b0007b416f81
diff --git a/src/gpu/gl/GrGpuGL.cpp b/src/gpu/gl/GrGpuGL.cpp
index 685d4e8..7a1f4be 100644
--- a/src/gpu/gl/GrGpuGL.cpp
+++ b/src/gpu/gl/GrGpuGL.cpp
@@ -891,7 +891,7 @@
 
 // good to set a break-point here to know when createTexture fails
 static GrTexture* return_null_texture() {
-//    SkASSERT(!"null texture");
+//    SkDEBUGFAIL("null texture");
     return NULL;
 }