Bug 737164 - Make ReadInputStreamToString fallible. r=bsmedberg

netwerk/base/public/nsNetUtil.h

@@ -1194,18 +1194,22 @@ NS_ReadInputStreamToBuffer(nsIInputStream *aInputStream,
     return rv; 
 }
 
+// external code can't see fallible_t
+#ifdef MOZILLA_INTERNAL_API
+
 inline nsresult
 NS_ReadInputStreamToString(nsIInputStream *aInputStream, 
                            nsACString &aDest,
                            PRUint32 aCount)
 {
-    aDest.SetLength(aCount);
-    if (aDest.Length() != aCount)
+    if (!aDest.SetLength(aCount, mozilla::fallible_t()))
         return NS_ERROR_OUT_OF_MEMORY;
     void* dest = aDest.BeginWriting();
     return NS_ReadInputStreamToBuffer(aInputStream, &dest, aCount);
 }
 
+#endif
+
 inline nsresult
 NS_LoadPersistentPropertiesFromURI(nsIPersistentProperties **result,
                                    nsIURI                   *uri,