[DevTools] Remove support for string event types.

third_party/WebKit/Source/devtools/front_end/ui_lazy/OverviewGrid.js

 /*
  * Copyright (C) 2013 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 82 matching lines @@
 
   /**
    * @param {number} left
    * @param {number} right
    */
   setWindow(left, right) {
     this._window._setWindow(left, right);
   }
 
   /**
-   * @param {string} eventType
+   * @param {symbol} eventType
    * @param {function(!Common.Event)} listener
    * @param {!Object=} thisObject
    * @return {!Common.EventTarget.EventDescriptor}
    */
   addEventListener(eventType, listener, thisObject) {
     return this._window.addEventListener(eventType, listener, thisObject);
   }
 
   /**
    * @param {number} zoomFactor
@@ skipping 320 matching lines @@
     position = Math.max(0, Math.min(position, this._width));
     if (position < this._startPosition) {
       this._windowSelector.style.left = position + 'px';
       this._windowSelector.style.right = this._width - this._startPosition + 'px';
     } else {
       this._windowSelector.style.left = this._startPosition + 'px';
       this._windowSelector.style.right = this._width - position + 'px';
     }
   }
 };