Bug 373393 - ASSERTION: Lying nsIInterfaceRequestor implementation! (mozilla/content/base/src/nsXMLHttpRequest.cpp)

fix by switching the getInterface implementation from setting Components.returnCode to throwing when an interface is not supported. Components.returnCode is currently broken (see bug 287107), and it's not clear when it gets fixed. The assertion is annoying and the original intent of returnCode was to use it for success codes anyway.

r=gavin

toolkit/mozapps/shared/src/badCertHandler.js

@@ -97,12 +97,7 @@ BadCertHandler.prototype = {
 
   // nsIInterfaceRequestor
   getInterface: function(iid) {
-    if (iid.equals(Components.interfaces.nsIBadCertListener) ||
-        iid.equals(Components.interfaces.nsIChannelEventSink))
-      return this;
-
-    Components.returnCode = Components.results.NS_ERROR_NO_INTERFACE;
-    return null;
+    return this.QueryInterface(iid);
   },
 
   // nsISupports

toolkit/mozapps/update/src/nsUpdateService.js.in

@@ -2572,8 +2572,7 @@ Downloader.prototype = {
           createInstance();
       return prompt.QueryInterface(iid);
     }
-    Components.returnCode = Components.results.NS_ERROR_NO_INTERFACE;
-    return null;
+    throw Components.results.NS_ERROR_NO_INTERFACE;
   },
    
   /**