ensure completion of async js scripts completes the fetch

When the fetch of asynchronous javascript scripts completed the
completion of html rendering was not processed leaving the state
machine waiting forever.

render/html_script.c

@@ -183,6 +183,13 @@ convert_script_async_cb(hlcache_handle *script,
 		break;
 	}
 
+	/* if there are no active fetches remaining begin post parse
+	 * conversion
+	 */
+	if (html_can_begin_conversion(parent)) {
+		html_begin_conversion(parent);
+	}
+
 	return NSERROR_OK;
 }