Invalid JS: Nested throw expressions

[no-longer-on-githu-b]

The following CoffeeScript code:

throw throw throw a

compiles to the following JavaScript code:

throw throw throw a;;;

which is invalid syntax in JavaScript.

Instead it should either compile to the following JavaScript code:

throw (function() {
    throw (function() {
        throw a;
    })();
})();

or be rejected by the CoffeeScript compiler.

Now this code is of course incredibly silly, but the CoffeeScript compiler should under no circumstance both accept the input and generate code with invalid syntax.

[jashkenas]

I don't think it should compile. That should be a syntax error.

[GeoffreyBooth]

See also #3709.

[GeoffreyBooth]

Fixed by #4664.