DevTools: rely upon shouldHideOnDetach when considering re-layout of elements and sources panels.

Source/devtools/front_end/ui/Widget.js

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * Copyright (C) 2011 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:
  * 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 88 matching lines @@
      * @return {boolean}
      */
     isShowing: function()
     {
         return this._isShowing;
     },
 
     /**
      * @return {boolean}
      */
-    _shouldHideOnDetach: function()
+    shouldHideOnDetach: function()
     {
         if (this._hideOnDetach)
             return true;
         for (var child of this._children) {
-            if (child._shouldHideOnDetach())
+            if (child.shouldHideOnDetach())
                 return true;
         }
         return false;
     },
 
     setHideOnDetach: function()
     {
         this._hideOnDetach = true;
     },
 
@@ skipping 151 matching lines @@
      */
     detach: function(overrideHideOnDetach)
     {
         var parentElement = this.element.parentElement;
         if (!parentElement)
             return;
 
         if (this._parentIsShowing())
             this._processWillHide();
 
-        if (!overrideHideOnDetach && this._shouldHideOnDetach()) {
+        if (!overrideHideOnDetach && this.shouldHideOnDetach()) {
             this.element.classList.add("hidden");
             this._visible = false;
             if (this._parentIsShowing())
                 this._processWasHidden();
             if (this._parentWidget && this._hasNonZeroConstraints())
                 this._parentWidget.invalidateConstraints();
             return;
         }
 
         // Force legal removal
@@ skipping 379 matching lines @@
 {
     WebInspector.Widget.__assert(!child.__widgetCounter && !child.__widget, "Attempt to remove element containing widget via regular DOM operation");
     return WebInspector.Widget._originalRemoveChild.call(this, child);
 }
 
 Element.prototype.removeChildren = function()
 {
     WebInspector.Widget.__assert(!this.__widgetCounter, "Attempt to remove element containing widget via regular DOM operation");
     WebInspector.Widget._originalRemoveChildren.call(this);
 }