Pushing to self-typed Array field causes all assignments to be lost

[jeffbcross]

Based on SHA ffbbb47

Pushing an object of a given type to an array field causes all properties of that type to no longer be minified.

Input:

export class Foo {
  private _foolist:Array<Foo>;
  add(f:Foo) {
    this._foolist.push(f);
  }
}

Output:

export class Foo {
  private _foolist:Array<Foo>;
  add(f:Foo) {
    this._foolist.push(f);
  }
}

If I change the array to be an array of string instead, here is the nicely-renamed output

export class Foo {
  private $:Array<string>;
  _(f:string) {
    this.$.push(f);
  }
}