Accept `Blob`s anywhere where a `Buffer` is currently accepted for writing

What is the problem this feature will solve?

Because Buffers aren't immutable, any time a Buffer is passed to something which will perform an asynchronous write, there is a concurrency hazard where the buffer could conceivably get modified before it gets a chance to be written. This can lead to bugs which are hard to track down. (I speak from experience.)

What is the feature you are proposing to solve the problem?

Anywhere where Buffer is currently accepted for a write operation, e.g. and perhaps most notably stream.Writable.write() and stream.Writable.end(), also make it acceptable to pass a Blob. Blobs are always immutable.

What alternatives have you considered?

Just keep using Buffers, mostly keep my fingers crossed, and sometimes make copies of Buffers as a safeguard.

(Note: It also makes sense to have a way to optionally have Blobs returned from readable streams, but I figure that'd be a different feature request.)

Start with the Node.js stream.Writable.write() and stream.Writable.end() entry points, then inspect other APIs that currently accept Buffer for asynchronous writes. Determine the required Blob behavior and update the relevant implementation, tests, and API documentation so Blob inputs are accepted consistently without changing readable-stream return behavior.