Properly skip checking for page breaks on empty text nodes (#2506)
Properly skip checking for page breaks on empty text nodes (#2506)

Before, page breaks before empty text nodes were not allowed, but they
were still checked; and as they report their line height as the space
needed, they could force a page break, which then would continue to
search backwards in the tree for an element that allowed a page break
(even though it would fit on the current page).

Based on work in #1356
Fixes #2468
dompdf/dompdf,dompdf/dompdf