Shadow offsets don't actually offset the content

[Gankra]

It appears that it only offsets the clipped/masked region:

From reftests/text/shadow-complex.yaml (with offset on red shadow set to [10, 10]) (mesa).

(Note the T at the start)

From running servo on https://gankro.github.io/blah/webtests/text.html (macos sierra):

(Note the m on "cillum")

[Gankra]

Note: I tried messing around with the bounds/local_rect a bunch and nothing happened. I assume you intended to place the content according to it, but forgot to, since the only place you seem to factor in offset is in translating that rect.

[glennw]

I'll look into these today.

[kvark]

Fixed by #1482