Various fixes resulting form Python testing

[max99x]

This pull includes a bunch of small fixes for errors I've discovered while testing empythoned. There's no unifying theme, so just check the commit messages. All llvm_gcc_0_0 tests pass.

[kripken]

1. Please use |Date.now()| instead of |new Date().getTime()|.
2. A shared library should never do static allocation, since it uses the main file's allocation stuff, I think? Let's make sure that is fixed in general instead of modifying specific appearances of ALLOC_STATIC to ALLOC_NORMAL. How about in the shared library preamble, defining a var ALLOC_STATIC to have the value of ALLOC_NORMAL?

[max99x]

1. Date.now() is not supported on some browsers, e.g. IE8. I don't suppose Emscripten compatible with IE8, is it?
2. I'm a little wary of shadowing a constant, and that is currently the only place where static allocations happen in shared libraries, since they have their own stripped down preamble/postamble and don't include library*.js.

[kripken]

1. Well, IE8 also doesn't support things like Canvas, and worse has such a slow JS engine it's doubtful Emscripten would be very useful for it. IE9 is really the first modern version. I would rather not clutter our code to support IE8, so I prefer Date.now().
2. Good point about the allocation stuff. Ok, let's do it that way, but please add a comment near that change regarding it being the only place we would potentially do static allocation in a shared library.

[max99x]

Done.