Revert of [LayoutNG] Move remaining ng_units structs to their own files (patchset #6 id:120001 of https://codereview.chromium.org/2721613003/ )

Reason for revert:
Causing link error on Android due to duplicate symbols: https://build.chromium.org/p/chromium.webkit/builders/Android%20Builder/builds/104531

Original issue's description:
> [LayoutNG] Move remaining ng_units structs to their own files
>
> R=mstensho@opera.com
>
> Review-Url: https://codereview.chromium.org/2721613003
> Cr-Commit-Position: refs/heads/master@{#453878}
> Committed: https://chromium.googlesource.com/chromium/src/+/480fa30589acd71427e3f902fd7916e87c41f5d9

TBR=mstensho@opera.com,eae@chromium.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Review-Url: https://codereview.chromium.org/2723023003
Cr-Commit-Position: refs/heads/master@{#453880}
52 files changed