nvda

90edc966 - Fix bug that stopped NVDA from announcing characters when backspacing rtl text from displayModel.

Fix bug that stopped NVDA from announcing characters when backspacing rtl text from displayModel. whitespace chunks in displayModels now have a valid window handle. Line start, line end and blank line whitespace chunks inherit the windowHandle of their actual rendering displayModel. Whitespace between two chunks with the same windowHandle on a line get that windowHandle. Whitespace between chunks with differing windowHandles on a line inherit the rendering displayModel's windowHandle.