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/utils/ios/SkOSFile_iOS.mm b/src/utils/ios/SkOSFile_iOS.mm
index a685761..e38ecfd 100755
--- a/src/utils/ios/SkOSFile_iOS.mm
+++ b/src/utils/ios/SkOSFile_iOS.mm
@@ -82,12 +82,12 @@
 }
 
 size_t sk_fwrite(const void* buffer, size_t byteCount, SkFILE* f) {
-    SkASSERT(!"Not supported yet");
+    SkDEBUGFAIL("Not supported yet");
     return 0;
 }
 
 void sk_fflush(SkFILE* f) {
-    SkASSERT(!"Not supported yet");
+    SkDEBUGFAIL("Not supported yet");
 }
 
 void sk_fclose(SkFILE* rec) {