DevTools: keep widgets in widget hierarchy upon hide, split attach/detach cycle from show/hide.

third_party/WebKit/LayoutTests/inspector/components/widget-events.html

Index: third_party/WebKit/LayoutTests/inspector/components/widget-events.html
diff --git a/third_party/WebKit/LayoutTests/inspector/components/widget-events.html b/third_party/WebKit/LayoutTests/inspector/components/widget-events.html
index 4174cf02cf9837471877b0dd3ebfeb50803d963b..e4cbc78c245f47dd9b3fb26a7d2e98e0f8191b54 100644
--- a/third_party/WebKit/LayoutTests/inspector/components/widget-events.html
+++ b/third_party/WebKit/LayoutTests/inspector/components/widget-events.html
@@ -151,13 +151,13 @@ function test()
             var parentWidget = new TestWidget("Parent");
             parentWidget.markAsRoot();
             var childWidget = new TestWidget("Child");
-            parentWidget.show(WebInspector.inspectorView.element);
+            parentWidget.show(document.body);
 
             parentWidget.doResize();
             childWidget.show(parentWidget.element);
             parentWidget.doResize();
             parentWidget.detach();
-            parentWidget.show(WebInspector.inspectorView.element);
+            parentWidget.show(document.body);
             childWidget.detach();
             parentWidget.detach();
             next();
@@ -341,6 +341,20 @@ function test()
             parentWidget.show(WebInspector.inspectorView.element);
             parentWidget.detach();
             next();
+        },
+
+        function testAlienParent(next)
+        {
+            var parentWidget1 = new TestWidget("Parent");
+            var parentWidget2 = new TestWidget("Parent");
+            var childWidget = new TestWidget("Child");
+            childWidget.attach(parentWidget1);
+            try {
+                childWidget.showWidget(parentWidget2.element);
+            } catch (e) {
+                InspectorTest.addResult(e);
+            }
+            next();
         }
     ]);
 }