fixed a caching issue with asynchronous requests in IE. r=igrcic, tschaub (closes #1896)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@8816 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Request.js

@@ -150,7 +150,15 @@ OpenLayers.Request = {
         };
         
         // send request (optionally with data) and return
-        request.send(config.data);
+        // call in a timeout for asynchronous requests so the return is
+        // available before readyState == 4 for cached docs
+        if(config.async === false) {
+            request.send(config.data);
+        } else {
+            window.setTimeout(function(){
+                request.send(config.data);
+            }, 0);
+        }
         return request;
     },