Revert of Move AppliedTextDecorationList to its own file. (patchset #2 id:20001 of )

Reason for revert:
Reverting since the BUILD file wasn't updated. Author is aware

Original issue's description:
> Move AppliedTextDecorationList to its own file.
> When we generate external types like Length in ComputedStyle, we specify
> the path to the type (e.g. "platform/Length"). We then deduce the name
> of the type from the path ("Length"). This means that the type must be
> stored in a file with the same name.
> This patch moves AppliedTextDecorationList to its own file so that it
> can be generated.
> BUG=628043
> Review-Url:
> Cr-Commit-Position: refs/heads/master@{#471653}
> Committed:,
# Skipping CQ checks because original CL landed less than 1 days ago.

Cr-Commit-Position: refs/heads/master@{#471656}
2 files changed