Revert of [LayoutNG] Remove simple constructors from NGPhysicalConstraintSpace. (patchset #2 id:20001 of https://codereview.chromium.org/2458253002/ )

Reason for revert:
Speculative revert due to failures in webkit_tests on WebKit Win7 (dbg) starting with https://build.chromium.org/p/chromium.webkit/builders/WebKit%20Win7%20%28dbg%29/builds/7940
(this was the only WebKit CL in the blamelist).

Original issue's description:
> [LayoutNG] Remove simple constructors from NGPhysicalConstraintSpace.
>
> BUG=635619
>
> Committed: https://crrev.com/08d3a096f20ce0196474108dc8a28ceddc3203c3
> Cr-Commit-Position: refs/heads/master@{#428757}

TBR=glebl@chromium.org,cbiesinger@chromium.org,ikilpatrick@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=635619

Review-Url: https://codereview.chromium.org/2470733002
Cr-Commit-Position: refs/heads/master@{#428975}
4 files changed