There are several places in the WebExtensions framework where we currently
need to repeatedly serialize and deserialize structured clone data as it
passes through message managers, which can lead to significant performance
issues.
This helper class lets us serialize a value directly from the source extension
context into an opaque blob, and then directly deserialize it into the target
context on the other end, with no X-ray overhead or clones into privileged
scopes in-between.
MozReview-Commit-ID: 4QzHi89onxc
--HG--
extra : rebase_source : 2ec196ca9ce9be90b7eadf136c938373ac7d3fdd
