SkPDF: Change handling of large-numbers in matricies.

re-do http://crrev.com/1438503002 right.

Also, add a unit test that asserts without this change.

BUG=skia:734
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1552263003

Review URL: https://codereview.chromium.org/1552263003
2 files changed