Bug 1032457 - Rename ExportOptions to ExportFunctionOptions. r=gabor
Bug 1032457 - Separate out cloning and non-cloning function forwarders. r=gabor

We're going to add functionality to the cloning version, and the non-cloning
version is going away.
Bug 1032457 - Implement the |allowCallbacks| parameter to exportFunction. r=gabor