v3.2.0: Reading array.length seems to trigger dirty flag

[Alex Edgcomb]

Issue Summary

Reading array.length then calling array.push() yields an error about updating a value after using it in a computation.

Steps to Reproduce

Minimal repro:

• component.js

import Component from '@glimmer/component';
import { tracked } from 'tracked-built-ins';

export default class MyComponent extends Component {
    myArray = tracked([]);

    constructor() {
        super(...arguments);
        this.myArray.push(this.myArray.length);
    }
}

• template.hbs (empty)

Error when component tries to load:

Uncaught Error: Assertion Failed: You attempted to update `_value` on `TrackedStorageImpl`, but it had already been used previously in the same computation.  Attempting to update a value after using it in a computation can cause logical errors, infinite revalidation bugs, and performance issues, and is not supported.

Technical details

tracked-built-ins@3.2.0
ember-source@4.11.0

Supporting information

This may have some relation to #29