Simplify line breaking and fix infinite loop on some documents.
Simplify line breaking and fix infinite loop on some documents.

This is non-optimal in some corner cases.

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