Don't let an empty intl.charset.default pref set the document charset to

the empty string.  Fall back to ISO-8859-1 in the script loader if there
is no other charset set.  Bug 118404, r=harishd, sr=jst

content/base/src/nsScriptLoader.cpp

@@ -691,6 +691,11 @@ nsScriptLoader::OnStreamComplete(nsIStreamLoader* aLoader,
 
     NS_ASSERTION(NS_SUCCEEDED(rv), "Could not get document charset!");
 
+    if (characterSet.IsEmpty()) {
+      // fall back to ISO-8851-1, see bug 118404
+      characterSet = NS_LITERAL_STRING("ISO-8859-1");
+    }
+    
     nsCOMPtr<nsICharsetConverterManager> charsetConv =
       do_GetService(kCharsetConverterManagerCID, &rv);
 

content/html/document/src/nsHTMLDocument.cpp

@@ -679,11 +679,11 @@ nsHTMLDocument::TryWeakDocTypeDefault(PRInt32& aCharsetSource,
   if (prefs) {
     nsXPIDLString defCharset;
     nsresult rv = prefs->GetLocalizedUnicharPref("intl.charset.default", getter_Copies(defCharset));
-    if (NS_SUCCEEDED(rv)) {
+    if (NS_SUCCEEDED(rv) && !defCharset.IsEmpty()) {
       aCharset.Assign(defCharset);
+      aCharsetSource = kCharsetFromWeakDocTypeDefault;
     }
   }
-  aCharsetSource = kCharsetFromWeakDocTypeDefault;
   return PR_TRUE;
 }