Because of how the class Collection adds the _events property to use for composition it produces some unexpected behaviors with some array methods like filter

To Reproduce
Steps:

• Create an empty collection: const collection = new Collection()
• Output Object.keys(collection)
  Expected
• An empty collection should have no keys or values
  Observed
• ['_events'] is the output

To Reproduce
Steps:

• Create an empty collection: const collection = new Collection()
• Output collection.filter(() => false) // or true, doesn't matter
  Expected
• An empty array should be the result
  Observed
• [0, _events: Events] is the output with filtering using true or false

Here is a small code snipped with the reproduction of the issue.

const emptyCollection = new Collection();

console.log(emptyCollection.length); // output: 0, expected

console.log(Object.keys(emptyCollection)); // output: ['_events'], not expected
  
const allIncluded = emptyCollection.filter(() => true);
console.log(allIncluded); // output: [0, _events: Events], not expected
  
const allExcluded = emptyCollection.filter(() => false); 
console.log(allExcluded); // output: [0, _events: Events], not expected

Environment (please select one):

• Code executes in browser (e.g: using script tag to load library)
• Packaged software (e.g: ES6 imports, react, angular, vue.js)
• Running headless (usually Node.js)

Notes:
I've seen a few places in the source code where some properties are sat as enumerable: false.
Would that do the trick to remove _events as enumerable from collection?
( And ids from Children that extends Collection)

Closing comment:
Thank you so much for building this project! I am playing around with building a collaborative whiteboard and the performance of two.js blows away some of competing products.