fix(treeshakable): use es5 syntax for treeshakable object

[HeadFox]

We still need to support IE-11 in our company (I hope we will drop it this year...) Declare function directly in the object is not supported by IE-11 get() are on the other side supported by IE-11

const module = {
  inject() {}
};

Instead, we need to declare it like this:

const module = {
  inject: function inject() {}
};