More slightly anal code generation stuff

[Rich-Harris]

REPL. When we have components without bindings, it doesn't really make sense to have an intermediate variable for the component's initial data:

// this...
var smileyFace = new SmileyFace({
  target: svg,
  _root: component._root || component,
  data: { x: 50, y: 200, size: 100 }
});

// ...not this:
var smileyFace_initialData = {
  x: 50,
  y: 200,
  size: 100
};
var smileyFace = new SmileyFace({
  target: svg,
  _root: component._root || component,
  data: smileyFace_initialData
});

On the SmileyFace component, the comment over namespace is preserved:

var template = (function () {
  return {
    // you can either use the shorthand 'svg', or the full
    // namespace: 'http://www.w3.org/2000/svg'. (I know
    // which one I prefer.)
    data () {
      return {
        x: 100,
        y: 100,
        size: 100
      };
    }
  };
}());

It would be cool if comments immediately preceding a removed property were removed along with it.