This Pull Request Fixes #8738.

When exporting a clause directly, TypeScript emits the member assignment to exports after the variable declaration of the member. This ignores all assignment statement afterwards.

Patch Summary:
When there is assignment operator expression =, +=, etc, check if the target is a member of export clause. If it is, make sure that the export clause is updated.

Behaviour before patch:

var foo = 2;
foo = 3;
export { foo }

compiles to

var foo = 2;
exports.foo = 2;
foo = 3;

Compile result after patch:

var foo = 2;
exports.foo = 2;
exports.foo = foo = 3;

Export alias are updated as well, I use the same code for variable declaration.