Add missing semicolon after do-while

[The spec says](https://tc39.github.io/ecma262/#sec-additions-and-changes-that-introduce-incompatibilities-with-prior-editions):

> In ECMAScript 2015, Automatic Semicolon Insertion adds a semicolon at the end of a do-while statement if the semicolon is missing. This change aligns the specification with the actual behaviour of most existing implementations.

See [ASI spec](https://tc39.github.io/ecma262/#sec-rules-of-automatic-semicolon-insertion). This if for example not implemented by IE 9, so transpiling it could actually provide some benefit.