[css-typed-om] Add support for flex properties.

This patch adds support for flex properties. Failing test because Blink
doesn't support 'content' for flex-basis yet.

Bug: 820299
Change-Id: Ie2df3fcaecda16d52ded1f90aab9f1df82e9e283
Reviewed-on: https://chromium-review.googlesource.com/963865
Reviewed-by: nainar <nainar@chromium.org>
Commit-Queue: Darren Shen <shend@chromium.org>
Cr-Commit-Position: refs/heads/master@{#543305}
10 files changed