increase init timer (fix #807)

lib/single-file/processors/frame-tree/content/content-frame-tree.js

@@ -52,7 +52,7 @@ const ACK_INIT_REQUEST_MESSAGE = "singlefile.frameTree.ackInitRequest";
 const CLEANUP_REQUEST_MESSAGE = "singlefile.frameTree.cleanupRequest";
 const INIT_RESPONSE_MESSAGE = "singlefile.frameTree.initResponse";
 const TARGET_ORIGIN = "*";
-const TIMEOUT_INIT_REQUEST_MESSAGE = 750;
+const TIMEOUT_INIT_REQUEST_MESSAGE = 5000;
 const TIMEOUT_INIT_RESPONSE_MESSAGE = 10000;
 const TOP_WINDOW_ID = "0";
 const WINDOW_ID_SEPARATOR = ".";