This test passes if the pages generated are identical for both vertical-lr and
horizontal-tb writing-modes by means of making the size of the content we are
printing equal to exactly the same number of pages being generated in each
This sizing is calculated like so:
1. It is important to note that irrespective of the writing-mode, the print
UI always lays out printed pages vertically. Therefore, it is possible
to equate the printed content of two different writing modes if both
cases generate the exact same number of pages (and of course no text on
the pages, which is why we use background color since it is independent
of writing mode).
2. To avoid an unnecessary vertical scrollbar (since scrolled content will be
clipped anyway in the reftest snapshot), the maximum number of 5X3in pages
that we should generate for the reftest snapshot are equal to 3.
3. Considering a margin of 0.5in on each side of the 5X3in page, we get the
size of the page content area to be 4X2in per page and to generate exactly 3
printed pages from this in horizontal-tb writing mode, we need a printable
area of 4X6in (as used below).
Similarly, the size for the test case printable area is calculated, only
considering a vertical-rl writing mode.
It is important to note here that when printing this test outside of the test
harness, the background color will not show since we omit printing and
previewing of background colors by default via the browser printing path.
<div style="background: teal; width:4in; height:6in;">