The API changes are due to enabling strict checks in TypeScript (via `strict: true`).
The payload size changes in `polyfills.js` are due to more browser APIs being patched in recent versions (e.g. `fetch`, `customElement v1`).
PR Close#28219
- Update tooling to support revised testing guide (PR #20697).
- Require jasmine upgrade for examples that use marble testing.
- Copy `cli/package.json` to `testing/` and add `jasmine-marbles`.
- Resolve merge conflicts created by `NgModules` guides.
PR Close#20165