Out of flow replaced blocks implementation.

spec: https://www.w3.org/TR/CSS2/visudet.html#inline-replaced-width

Main changes are:

# ng_out_of_flow_layout + ng_absolute_utils
If an element has an intrinsic size, and size is not explicit, use
intrinsic size instead.

# layout_ng_block_flow
If an oof block's containing block is LegacyLayout, and width/height are Auto, initialize constraint 
space with legacy width/height, unless width is shrink-to-fit.

Bug: 740993
Change-Id: If8540ab4de4211d4f332c0cb772a53bd247ab19c
Reviewed-on: https://chromium-review.googlesource.com/570927
Commit-Queue: Aleks Totic <atotic@chromium.org>
Reviewed-by: Christian Biesinger <cbiesinger@chromium.org>
Reviewed-by: Ian Kilpatrick <ikilpatrick@chromium.org>
Cr-Commit-Position: refs/heads/master@{#489917}
13 files changed