Remove dead code

Change-Id: I59fb7843d5c9a6cf2873b6d668d0e9dccff316d2
Remove dead code

Change-Id: Id522113f1ba0c9e7b1356acc01a79e0e90a5e752
Remove dead code

Change-Id: Ia9035189bd01d3a3e5e3222760fc392f3f78880f
Reduce IAccessibleTabListBox to what's actually used

...the calls to getAccessibleChild(0) and getHeaderBar(BBYTE_COLUMNHEADERBAR)
ultimately all ended up at
AccessibleBrowseBox::implGetHeaderBar(BBTYPE_COLUMNHEADERBAR).

Change-Id: Ie25659e19d0d1ce2dcde2d1440ecc69b4fa265b0