Revert of Serializer: support all alignment kinds. (patchset #3 id:40001 of https...

Revert of Serializer: support all alignment kinds. (patchset #3 id:40001 of https://codereview.chromium.org/1179873003/)

Reason for revert:
[Sheriff] Breaks arm debug compile:
http://build.chromium.org/p/client.v8/builders/V8%20Arm%20-%20debug%20builder/builds/4308

Original issue's description:
> Serializer: support all alignment kinds.
>
> We use an alignment prefix for unusual alignment kinds (not kWordAligned).
> This will cause new objects to be aligned in ReadObject, and back references
> to be aligned to skip padding.
>
> The motivation to change the undefined next sentinel in WeakCell is this:
> When the deserializer aligns an object, it requires filler maps to already
> exist to create filler objects as padding. However, deserializing the
> filler map leads to deserializing NaN, which as heap number is aligned:
> filler map > meta map > weak cell cache > undefined > NaN
> If we use the-hole instead of undefined as sentinel, it works.
>
> R=jochen@chromium.org,bbudge@chromium.org
> BUG=v8:4178
> LOG=N
>
> Committed: https://crrev.com/2146ab75387d47eef6582bd8c2d0cfc6c42b68b6
> Cr-Commit-Position: refs/heads/master@{#29044}

TBR=jochen@chromium.org,bbudge@chromium.org,yangguo@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=v8:4178

Review URL: https://codereview.chromium.org/1173253006

Cr-Commit-Position: refs/heads/master@{#29045}