DevTools: Make target on TimelineRecord nullable

Source/devtools/front_end/timeline/TimelineView.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  * Copyright (C) 2012 Intel 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.
@@ skipping 819 matching lines @@
     _highlightQuad: function(rowElement)
     {
         if (!rowElement || !rowElement.row)
             return false;
         var presentationRecord = rowElement.row._record;
         if (presentationRecord.coalesced())
             return false;
         var record = presentationRecord.record();
         if (this._highlightedQuadRecord === record)
             return true;
-        this._highlightedQuadRecord = record;
 
         var quad = this._uiUtils.highlightQuadForRecord(record);
-        if (!quad)
+        var target = record.target();
+        if (!quad || !target)
             return false;
-        record.target().domAgent().highlightQuad(quad, WebInspector.Color.PageHighlight.Content.toProtocolRGBA(), WebInspector.Color.PageHighlight.ContentOutline.toProtocolRGBA());
+        this._highlightedQuadRecord = record;
+        target.domAgent().highlightQuad(quad, WebInspector.Color.PageHighlight.Content.toProtocolRGBA(), WebInspector.Color.PageHighlight.ContentOutline.toProtocolRGBA());
         return true;
     },
 
     _hideQuadHighlight: function()
     {
-        if (this._highlightedQuadRecord) {
-            this._highlightedQuadRecord.target().domAgent().hideHighlight();
+        var target = this._highlightedQuadRecord ? this._highlightedQuadRecord.target() : null;
+        if (target)
+            target.domAgent().hideHighlight();
+
+        if (this._highlightedQuadRecord)
             delete this._highlightedQuadRecord;
-        }
     },
 
     /**
      * @param {!Element} anchor
      * @param {!WebInspector.Popover} popover
      */
     _showPopover: function(anchor, popover)
     {
         if (!anchor._tasksInfo)
             return;
@@ skipping 209 matching lines @@
 
         if (this._dataElement.firstChild)
             this._dataElement.removeChildren();
 
         this._warningElement.classList.toggle("hidden", !presentationRecord.hasWarnings() && !presentationRecord.childHasWarnings());
         this._warningElement.classList.toggle("timeline-tree-item-child-warning", presentationRecord.childHasWarnings() && !presentationRecord.hasWarnings());
 
         if (presentationRecord.coalesced()) {
             this._dataElement.createTextChild(WebInspector.UIString("× %d", presentationRecord.presentationChildren().length));
         } else {
-            var detailsNode = uiUtils.buildDetailsNode(record, this._linkifier, loadedFromFile);
+            var detailsNode = uiUtils.buildDetailsNode(record, this._linkifier);
             if (detailsNode) {
                 this._dataElement.createTextChild("(");
                 this._dataElement.appendChild(detailsNode);
                 this._dataElement.createTextChild(")");
             }
         }
 
         this._expandArrowElement.classList.toggle("parent", presentationRecord.expandable());
         this._expandArrowElement.classList.toggle("expanded", !!presentationRecord.visibleChildrenCount());
         this._record.setListRow(this);
@@ skipping 200 matching lines @@
         } else {
             this._element.classList.add("hidden");
         }
     },
 
     _dispose: function()
     {
         this._element.remove();
     }
 }