Match stream.WritableStream.end to stream.Writable.end
Match stream.WritableStream.end to stream.Writable.end

Until we decide what to do with WritableStream, fix it to avoid
producing any warnings.

Signed-off-by: Kevin Locke <ffb4761cba839470133bee36aeb139f58d7dbaa9@kevinlocke.name>

keunwoo/node.js-closure-compiler-externs,dcodeIO/node.js-closure-compiler-externs