msxml3: Remove attach_xmldoc(This, NULL) calls.

This->node should never be zero. Each IXMLDOMNode (and derived interfaces)
always represents a present libxml data object. There is no no-data
IXMLDOMNode, although there might be documents without a root element.

dlls/msxml3/domdoc.c

@@ -1364,8 +1364,6 @@ static HRESULT WINAPI domdoc_load(
 
     assert( This->node );
 
-    attach_xmldoc(This->node, NULL);
-
     switch( V_VT(&xmlSource) )
     {
     case VT_BSTR:
@@ -1549,8 +1547,6 @@ static HRESULT WINAPI domdoc_loadXML(
 
     assert ( This->node );
 
-    attach_xmldoc( This->node, NULL );
-
     if ( isSuccessful )
     {
         *isSuccessful = VARIANT_FALSE;