DOMWindow::navigator should return navigator w/o frame when detached.

Source/core/frame/LocalDOMWindow.cpp

Index: Source/core/frame/LocalDOMWindow.cpp
diff --git a/Source/core/frame/LocalDOMWindow.cpp b/Source/core/frame/LocalDOMWindow.cpp
index 0ffefbc9f3026c909f369bca438422e598acdad5..3feb9960f5f950b364295674b2b39d3625c93fb7 100644
--- a/Source/core/frame/LocalDOMWindow.cpp
+++ b/Source/core/frame/LocalDOMWindow.cpp
@@ -661,6 +661,12 @@ ApplicationCache* LocalDOMWindow::applicationCache() const
 
 Navigator* LocalDOMWindow::navigator() const
 {
+    if (frame() && frame()->domWindow() != this) {

[haraken, 2015/08/24 02:22:15]

It would be better to use:

  if (!isCurrentlyDisplayedInFrame())
    return nullptr;

[yhirano, 2015/08/24 03:27:11]

Done.

+        // This window is already detached.
+        ASSERT(!m_navigator);
+        return nullptr;
+    }
+
     if (!m_navigator)
         m_navigator = Navigator::create(frame());
     return m_navigator.get();