- Changes WASM serialization to copy misaligned code into an aligned
  buffer before relocating. This extra copy will eventually go away
  when code is mapped into the process.
- Serialized code buffers no longer need padding to align their
  contents.

Change-Id: Ib016c69b5099a4cf039dcd3d36a48f076033227c
Reviewed-on: https://chromium-review.googlesource.com/1060471Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Bill Budge <bbudge@chromium.org>
Cr-Commit-Position: refs/heads/master@{#53219}