Corrected codegen to support shadowed module names.

[ahejlsberg]

Fixes #601.

[ahejlsberg]

For the example

module X.M {
    export var x = false;

    function q(M) {
    }

    M.x = true;
}

we would previously emit

var X;
(function (X) {
    (function (_M) {
        _M.x = false;
        function q(M) {
        }
        M.x = true;  // Crash here, M not yet initialized
    })(X.M || (X.M = {}));
    var M = X.M;
})(X || (X = {}));

With this change we now emit:

var X;
(function (X) {
    var M;
    (function (_M) {
        _M.x = false;
        function q(M) {
        }
        M.x = true;
    })(M = X.M || (X.M = {}));  // Initialize both M and X.M
})(X || (X = {}));

This also brings our code generation for exported modules more in line with non-exported modules by always declaring the local variable before the anonymous function.

[mhegazy]

👍

[sparecycles]

👍 Thanks!