Bug 921454 - Allow chromeOnlyContent to work for non-chrome XBL documents. r=smaug

Given that we turn off XBL for the web, this just affects remote XUL/XBL, in
particular our tests. And it's expedient for NAC testing to be able to test
with an in-content XBL binding.

content/xbl/src/nsXBLPrototypeBinding.cpp

@@ -208,8 +208,7 @@ nsXBLPrototypeBinding::SetBindingElement(nsIContent* aElement)
                             nsGkAtoms::_false, eCaseMatters))
     mInheritStyle = false;
 
-  mChromeOnlyContent = IsChrome() &&
+  mChromeOnlyContent = mBinding->AttrValueIs(kNameSpaceID_None,
-                       mBinding->AttrValueIs(kNameSpaceID_None,
                                              nsGkAtoms::chromeOnlyContent,
                                              nsGkAtoms::_true, eCaseMatters);
 }