Function name shortened, but not function call

There seems to be a problem with shortening names in some cases. Below is an example.

```js
{
addOnclick: function(){
element.onclick = ()=>{this.foo("some string")};
},

foo: function(str){
//do things
}
}
```

I get: "this.foo is not a function"
What it looks like is happening is that it is changing the name of the function, but it is not changing the call to that function. It seems to do this everywhere that I have this format as far as I can tell. It works with browserify of course, but it breaks with tinyify.