Add sinks to provide synchronous access to events.
These are useful when doing chunked conversion in a synchronous context.
Closes #2
R=lrn@google.com
Review URL: https://codereview.chromium.org//1911053002 .
This package contains encoders and decoders for converting between different data representations. It's the external counterpart of the dart:convert core library, and contains less-central APIs and APIs that need more flexible versioning.
