Revert of Remove unneeded DocumentLoader null check in WindowProxy. (…

…patchset #1 id:1 of https://codereview.chromium.org/797483003/)

Reason for revert:
Test plugins/js-from-destroy.html starts crashing on Mac.
Flakiness Dashboard: http://goo.gl/YID0Ti

Original issue's description:
> Remove unneeded DocumentLoader null check in WindowProxy.
> 
> BUG=none
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=186983

TBR=haraken@chromium.org,dcarney@chromium.org,dcheng@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=none

Review URL: https://codereview.chromium.org/794113005

git-svn-id: svn://svn.chromium.org/blink/trunk@187020 bbb929c8-8fbe-4397-9dbb-9b2b20218538

Source/bindings/core/v8/WindowProxy.cpp

@@ -250,6 +250,11 @@ bool WindowProxy::initialize()
 
 void WindowProxy::createContext()
 {
+    // The documentLoader pointer could be 0 during frame shutdown.
+    // FIXME: Can we remove this check?
+    if (!m_frame->loader().documentLoader())
+        return;
+
     // Create a new environment using an empty template for the shadow
     // object. Reuse the global object if one has been created earlier.
     v8::Handle<v8::ObjectTemplate> globalTemplate = V8Window::getShadowObjectTemplate(m_isolate);