Revert &quotRemove old serializer&quot It caused a regression, crbug.com/510422

      > Remove old serializer
>
> Remove old serializer (WebPageSerializerImpl) and its tests
> (WebPageSerializerTest and resources) and use PageSerializer for all
> serialization tasks in WebPageSerializer.
>
> --
>
> This review is part of set aiming to merge the two existing page
> serializers, WebPageSerializerImpl and PageSerializer into the latter
> one.
>
> In addition to this it moves all the old tests from
> WebPageNewSerializerTest and WebPageSerializerTest to the newer
> PageSerializerTest structure and splits out a test for MHTML into the
> MHTMLTest file.
>
> Note: This is a rebase and split of
> https://codereview.chromium.org/68613003 from Opera which was reverted
> due to failing tests. In addition to the rebase some smaller fixes was
> done to accommodate to changes in the code from when it was first
> landed.
>
> BUG=328354
> R=hajimehoshi@chromium.org
>
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=198151
>
> Review URL: https://codereview.chromium.org/1177733003

BUG=328354,510422
TBR=hajimehoshi@chromium.org,gustav.tiger@sonymobile.com

Review URL: https://codereview.chromium.org/1295063002

git-svn-id: svn://svn.chromium.org/blink/trunk@200628 bbb929c8-8fbe-4397-9dbb-9b2b20218538