Cache intermediate results for intrinsic widths on tables.
Cache intermediate results for intrinsic widths on tables.

This fixes huges performance problems when a large table is split
across many pages.

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