The underlying problem is that `es5-shim` polyfills `Array.prototype`
methods in IE8, but it can't actually make them non-enumerable, so
`_.extend` copies them, because it doesn't check `hasOwnProperty`.
This probably calls for a more general audit of for-in loops over objects
that could be Arrays, especially within underscore.
The jscript plugin works around various limitations of older Internet
Explorer versions, in particular those described here:
http://kiro.me/blog/nfe_dilemma.html
This included removing some internal version constraints. It would be
nice if package A could say "use B@2.0.0" (when both have changed), but
when they're both in the release, we need to make a release that has a
B@2.0.0-rc in it, which doesn't match that constraint. Fortunately,
constraints aren't necessary within a release anyway.
This package will be installed by default for all new apps and packages.
Passing the {transpile:false} option to api.addFiles makes it possible for
a dependent package to specify that some files should not be processed
through babel-compiler.
