Streams have multiple parts that can be JS objects from different compartments.
For example, the [[reader]] internal slot of a stream can point to a reader
object in another compartment.
This patch makes the ReadableStream implementation robust against mixing and
matching stream-related objects and methods from different globals.
This also removes ReadableStreamBYOBReader and ReadableStreamBYOBRequest for
now, with a view toward enabling basic ReadableStream features by default in
bug 1389628.
Differential Revision: https://phabricator.services.mozilla.com/D8450
--HG--
extra : rebase_source : 71d73bed5bc82557efcb6b1ecb231275fd3e1189
extra : amend_source : de29f663b9929eb2858b23cc6f4e7ba97b23a28c
extra : source : f91eb962df6a06d5f51ad13caa2a4a9c2947f293
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