Add typed array types to js2-node-externs

node.js has supported typed arrays since 0.6:

https://github.com/joyent/node/wiki/API-changes-between-v0.4-and-v0.6
https://github.com/joyent/node/issues/1322
https://github.com/joyent/node/commit/97b0000
Add js2-typed-array-externs, js2-set-default-externs
Merge pull request #101 from pd/node-typed-arrays

Add typed array externs