Throw JS / Python exceptions according to execution context

[GoogleCodeExporter]

Upfront, I know this sounds quite correct, especialy since an uncaught excepton 
will kill an app in python by design, but in JS/Browser/CEF it's a bit 
different, so bare with me...

Here is a trivial example:

We bind this Python function to the browser...
---cut---

def PyFunc(a, b, c):
    return [a, b, c]


--uncut--


And use it like so:

---cut---

var lst = PyFunc(1, 2)


--uncut--

This topples the while app first raising a python exception (logical) and then 
a memory error (possibly related to Issue #2).

Here is the obvious Python error:
'''
TypeError: PyFunc() takes exactly 3 arguments (2 given)
'''

Expected behavior:
- raise a JS exception.

Original issue reported on code.google.com by alex.na...@gmail.com on 28 Aug 2012 at 12:17