Clip from 1025px (which is what this test is about) to 1024px because the
GLES2 renderer in CI otherwise scales its repeat node offscreen for the
--repeat version of this test and that conveniently produces off-by-one
misrenderings everywhere.
However, we need to keep the image large enough so that all the glyphs
are actually rendered and not skipped which would not overflow the
cache.
d14932474b