XHTML modularization bugs

This is on the CR version on the XHTML modularization spec.

1. In the basic tables abstract module, the scope attribute on the th
element allows values rowgroup and colgroup.  These are not allowed in
the DTD nor does the td element allow them.

2. In the basic tables abstract module, the table element has a width
attribute, but the DTD does not.

3. In the iframe abstract module, the content model for iframe should be
(Flow | PCDATA)*. The DTD module is also missing the PCDATA.

4. In the iframe abstract module, the datatype for the height attribute
should be Length not Pixels.

5. In the legacy abstract module, the font element should have Core and
I18n attributes rather than Common attributes.

6. The legacy abstract module omits the dir, menu and isindex elements,
which are included in the DTD.

7. The legacy DTD module adds a target attribute to the a element. This
is already handled by the target module.

8. The content module for applet in the DTD module is missing #PCDATA.

James