Fix dom_element_set_attribute() to use dom_attr_set_value() to replace the value of an existing attribute -- attribute values are stored as a tree of child nodes, not as a string attached to the nodeValue pointer.
Fix dom_element_set_attribute() to use dom_attr_set_value() to replace the value of an existing attribute -- attribute values are stored as a tree of child nodes, not as a string attached to the nodeValue pointer.

svn path=/trunk/dom/; revision=3580

Achal-Aggarwal/libdom,prepare/netsurf_libdom,dunkelstern/libdom,prepare/netsurf_libdom,prepare/netsurf_libdom,dunkelstern/libdom,prepare/netsurf_libdom,Achal-Aggarwal/libdom,dunkelstern/libdom,Achal-Aggarwal/libdom,Achal-Aggarwal/libdom,dunkelstern/libdom,dunkelstern/libdom,Achal-Aggarwal/libdom,dunkelstern/libdom,prepare/netsurf_libdom,prepare/netsurf_libdom,Achal-Aggarwal/libdom