[Devtools] Prepare network log view for grouping support

third_party/WebKit/Source/devtools/front_end/sdk/NetworkRequest.js

 /*
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 1084 matching lines @@
   }
 
   /**
    * @return {!Set<!SDK.NetworkRequest>}
    */
   _initiatorChain() {
     if (this._initiatorChainCache)
       return this._initiatorChainCache;
     this._initiatorChainCache = new Set();
     var request = this;
-    while (request) {
+    while (request && !this._initiatorChainCache.has(request)) {
       this._initiatorChainCache.add(request);
       request = request.initiatorRequest();
     }
     return this._initiatorChainCache;
   }
 
   /**
    * @return {!Array.<!SDK.NetworkRequest.WebSocketFrame>}
    */
   frames() {
@@ skipping 106 matching lines @@
 };
 
 /** @typedef {!{type: SDK.NetworkRequest.WebSocketFrameType, time: number, text: string, opCode: number, mask: boolean}} */
 SDK.NetworkRequest.WebSocketFrame;
 
 /** @typedef {!{time: number, eventName: string, eventId: string, data: string}} */
 SDK.NetworkRequest.EventSourceMessage;
 
 /** @typedef {!{initiators: !Set<!SDK.NetworkRequest>, initiated: !Set<!SDK.NetworkRequest>}} */
 SDK.NetworkRequest.InitiatorGraph;