nvda

557bdfbf - Some implementations of IAccessible2 use a table-cell-index object attribute on table cell objects to identify the cell in IAccessibleTable methods. However other implementations use the indexInParent property. Gecko's implementation of IAccessible2 uses table-cell-index, and not indexInParent. To support both, and to make sure that we no longer announce some redundant and incorrect cell information on some Gecko textFrames in tables, IAccessible NVDAObject now has a class variable called IAccessibleTableUsesTableCellIndexAttrib. This boolean value is checked when collecting cell information, and if it is true then table-cell-index is used, if its false then indexInParent is used. By default this value is False as up until recently the IAccessible2 spec said to use indexInParent. However the Mozilla IAccessible NVDAObject has this value set to true. Fixes #338