Add tests for whitespace processing.
Add tests for whitespace processing.

andrewleech/WeasyPrint,andrewleech/WeasyPrint,Kozea/WeasyPrint,prepare/TestWeasyPrint,Kozea/WeasyPrint,marclaporte/WeasyPrint,marclaporte/WeasyPrint,prepare/TestWeasyPrint,jasco/WeasyPrint,jasco/WeasyPrint