[css-typed-om] Handle out-of-range values correctly.

Currently, when we set width to something like -1, we would get an
invalid value for width. According to the spec [1], we should be
wrapping the invalid value in a calc.

This patch wraps invalid values in calc, and changes the test harness
to allow us to test this.

Bug: 545318
Change-Id: I71769e1bc69164c9b7dcf0d2c54ca06b623b5d9e
Reviewed-on: https://chromium-review.googlesource.com/923603
Commit-Queue: Darren Shen <shend@chromium.org>
Reviewed-by: nainar <nainar@chromium.org>
Cr-Commit-Position: refs/heads/master@{#537685}
8 files changed