This CL enables WebDevs to provide an NDEFMessageInit dictionary as
NDEFRecordInit#data, to create a ndef record whose payload is a ndef
message (thus we get embedded records), then serializes the payload ndef
message to bytes as payload when writing the record into a nfc tag.

The spec change:
https://github.com/w3c/web-nfc/pull/359

BUG=520391

Change-Id: I4120092d7a818d047f7e1d30ce891a8a84180b48
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1983512
Commit-Queue: Leon Han <[email protected]>
Reviewed-by: Reilly Grant <[email protected]>
Cr-Commit-Position: refs/heads/master@{#729267}