Add an option for generating synchronously loading debug and assert libraries.

[mrburrito]

In some instances, it would be useful to have a version of the assert and debug libraries that is a single file instead of the asynchronously loading files that are currently generated. A specific use case is hosting the compiled and assert/debug code from a secured web server that needs to modify the returned JavaScript at request time. This is nearly impossible to do with the async code because the library needs to have a single entry point and we don't want to expose all of the internal files from the web server.