Devtools UI: Fix tooltip issues

Source/devtools/front_end/elements/ElementsTreeElement.js

 /*
  * Copyright (C) 2007, 2008 Apple Inc.  All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  * Copyright (C) 2009 Joseph Pecoraro
  *
  * 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
@@ skipping 1114 matching lines @@
         /**
          * @this {WebInspector.ElementsTreeElement}
          */
         function setTitle()
         {
             this._decorationsElement.removeChildren();
             if (!decorations.length && !descendantDecorations.length)
                 return;
 
             var colors = new Set();
-            var titles = [];
+            var titles = createElement("div");
 
             for (var decoration of decorations) {
-                titles.push(decoration.title);
+                var titleElement = titles.createChild("div");
+                titleElement.textContent = decoration.title;
                 colors.add(decoration.color);
             }
             if (this.expanded && !decorations.length)
                 return;
 
             var descendantColors = new Set();
             if (descendantDecorations.length) {
-                titles.push(WebInspector.UIString("Children:"));
+                var element = titles.createChild("div");
+                element.textContent = WebInspector.UIString("Children:");
                 for (var decoration of descendantDecorations) {
-                    titles.push(decoration.title);
+                    element = titles.createChild("div");
+                    element.style.marginLeft = "15px";
+                    element.textContent = decoration.title;
                     descendantColors.add(decoration.color);
                 }
             }
 
             var offset = 0;
             processColors.call(this, colors, "elements-gutter-decoration");
             if (!this.expanded)
                 processColors.call(this, descendantColors, "elements-gutter-decoration elements-has-decorated-children");
-            WebInspector.Tooltip.install(this._decorationsElement, titles.join("\n"));
+            WebInspector.Tooltip.install(this._decorationsElement, titles);
 
             /**
              * @param {!Set<string>} colors
              * @param {string} className
              * @this {WebInspector.ElementsTreeElement}
              */
             function processColors(colors, className)
             {
                 for (var color of colors) {
                     var child = this._decorationsElement.createChild("div", className);
@@ skipping 412 matching lines @@
 
             if (object)
                 object.callFunction(scrollIntoView);
         }
 
         this._node.resolveToObject("", scrollIntoViewCallback);
     },
 
     __proto__: TreeElement.prototype
 }