fix(instrumenter): don't mutate constructor blocks with initialized class properties

[nicojs]

Don't mutate constructor block statements when the class contains initialized class properties. For example:

class Foo extends Baz {
  bar = 'bar';
  constructor() {  // Don't mutate this block!
     super();
  }
}

If you mutate the constructor block above, and TypeScript transpiles the code, it will call this.bar before the super() is initiated. Resulting in a runtime error.

Fixes #2474