servo/servo — pull request #3631 by pcwalton (2014-10-10 05:24:17+00:00)
Title: layout: Store containing block inline-size separately rather than writing it to a temporary location and overwriting it.

This makes layout more idempotent, which is important for incremental
layout.

Also converts `is_root` to a set of flags and fixes a `TODO` concerning
percentage inline heights of images.

r? @glennw