DevTools: migrate treeoutline from hasChildren to is/setExpandable().

Source/devtools/front_end/sources/NavigatorView.js

Index: Source/devtools/front_end/sources/NavigatorView.js
diff --git a/Source/devtools/front_end/sources/NavigatorView.js b/Source/devtools/front_end/sources/NavigatorView.js
index 56f79abd467bc8793d220740ba1c486dbb3526ac..65141a184eb80f050776915ab301ad0da718a933 100644
--- a/Source/devtools/front_end/sources/NavigatorView.js
+++ b/Source/devtools/front_end/sources/NavigatorView.js
@@ -649,13 +649,13 @@ WebInspector.NavigatorView._treeElementsCompare = function compare(treeElement1,
  * @param {string} type
  * @param {string} title
  * @param {!Array.<string>} iconClasses
- * @param {boolean} hasChildren
+ * @param {boolean} expandable
  * @param {boolean=} noIcon
  */
-WebInspector.BaseNavigatorTreeElement = function(type, title, iconClasses, hasChildren, noIcon)
+WebInspector.BaseNavigatorTreeElement = function(type, title, iconClasses, expandable, noIcon)
 {
     this._type = type;
-    TreeElement.call(this, "", hasChildren);
+    TreeElement.call(this, "", expandable);
     this._titleText = title;
     this._iconClasses = iconClasses;
     this._noIcon = noIcon;