Part of the fix for bug 76567 (load viewsource.css on demand rather than at startup) and bug 60892 (show title on the viewsource window) r=harishd,brendan sr=jst

suite/locales/en-US/chrome/browser/viewSource.dtd

@@ -6,4 +6,4 @@
 <!ENTITY mainWindow.titlemodifier "&brandShortName;"> 
 <!-- LOCALIZATION NOTE (mainWindow.titlemodifierseperator) : DONT_TRANSLATE -->
 <!ENTITY mainWindow.titlemodifierseperator " - ">
-<!ENTITY mainWindow.preface "Source for: "> 
+<!ENTITY mainWindow.preface "Source of: ">