Revert of Show service worker navigation preload requests in DevTools Network tab

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 1118 matching lines @@
   ResponseHeadersChanged: Symbol('ResponseHeadersChanged'),
   WebsocketFrameAdded: Symbol('WebsocketFrameAdded'),
   EventSourceMessageAdded: Symbol('EventSourceMessageAdded')
 };
 
 /** @enum {string} */
 SDK.NetworkRequest.InitiatorType = {
   Other: 'other',
   Parser: 'parser',
   Redirect: 'redirect',
-  Script: 'script',
-  Preload: 'preload'
+  Script: 'script'
 };
 
 /** @typedef {!{name: string, value: string}} */
 SDK.NetworkRequest.NameValue;
 
 /** @enum {string} */
 SDK.NetworkRequest.WebSocketFrameType = {
   Send: 'send',
   Receive: 'receive',
   Error: 'error'
 };
 
 /** @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;