DevTools: preload treeoutline triangles image

third_party/WebKit/Source/devtools/front_end/ui/treeoutline.js

 /*
  * Copyright (C) 2007 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 1195 matching lines @@
     var paddingLeftValue = window.getComputedStyle(this._listItemNode).paddingLeft;
     console.assert(paddingLeftValue.endsWith('px'));
     var computedLeftPadding = parseFloat(paddingLeftValue);
     var left = this._listItemNode.totalOffsetLeft() + computedLeftPadding;
     return event.pageX >= left && event.pageX <= left + UI.TreeElement._ArrowToggleWidth && this._expandable;
   }
 };
 
 /** @const */
 UI.TreeElement._ArrowToggleWidth = 10;
+
+(function() {

[pfeldman, 2017/02/13 18:18:12]

Is this temporary? I wish all the generic images were a part of a single sprite.

+  var img = new Image();
+  if (window.devicePixelRatio > 1)
+    img.src = 'Images/treeoutlineTriangles_2x.png';
+  else
+    img.src = 'Images/treeoutlineTriangles.png';
+  UI.TreeElement._imagePreload = img;
+})();