Bug 629682 - Add a better warning message for SVG-as-an-image external resources being blocked. r=dholbert

dom/base/nsDataDocumentContentPolicy.cpp

@@ -92,7 +92,7 @@ nsDataDocumentContentPolicy::ShouldLoad(uint32_t aContentType,
           requestingPrincipal->GetURI(getter_AddRefs(principalURI));
         if (NS_SUCCEEDED(rv) && principalURI) {
           nsScriptSecurityManager::ReportError(
-            nullptr, NS_LITERAL_STRING("CheckSameOriginError"), principalURI,
+            nullptr, NS_LITERAL_STRING("ExternalDataError"), principalURI,
             aContentLocation);
         }
       }

dom/locales/en-US/chrome/security/caps.properties

@@ -4,6 +4,7 @@
 CheckMessage = Remember this decision
 CheckLoadURIError = Security Error: Content at %S may not load or link to %S.
 CheckSameOriginError = Security Error: Content at %S may not load data from %S.
+ExternalDataError = Security Error: Content at %S attempted to load %S, but may not load external data when being used as an image. 
 
 # LOCALIZATION NOTE (GetPropertyDeniedOrigins):
 # %1$S is the origin of the script which was denied access.