Note that this is only triggered when coffeescript manages to output invalid JS,
which should be unlikely.
This does remove the feature where lines and columns were suppressed for parse
errors in the output of template compilation. but (a) that shouldn't happen,
and (b) we'll fix this by implementing source maps for spacebars.
@export is now an error in test slices.
This is preparation for ensuring that any slice with exports has at least
"Package.foo = {}"; without this commit, both the use and test slice would (with
that change) try to overwrite Package.foo.
Remove the attempt to allow @export in 'use strict' CoffeeScript files:
ECMAScript 'use strict' is fundamentally incompatible with our implementation of
exports, and it was probably a bug that this used to work at all.
