Bunch of misc fixes and preparations for further improvements. The location changes are especially important later when we'll use outer windows everywhere we pass them to external callers (such as script engines, since inner windows are an implementation detail and all operations otherwise should go through the outer window "proxy").
-- v3: mshtml: Embed the HTMLLocation into the outer window. mshtml: Tie window.location to the outer window. mshtml: Simplify dynamic props unlinking. mshtml: Traverse and unlink builtin func disps. mshtml: Return undefined from window.XMLHttpRequest for uninitialized jscript: Pass the correct ServiceProvider when invoking external prop. mshtml: Use Scrollbar_Auto as default for vertical scrollbars. include/mshtml: Add the other IHTMLEventObj* interfaces.