This allows Angular to error on unknown properties,
allowing applications that don’t use custom elements
to get better error reporting.
Part of #10043
BREAKING CHANGE:
- By default, Angular will error during parsing
on unknown properties,
even if they are on elements with a `-` in their name
(aka custom elements). If you application is using
custom elements, fill the new parameter `@NgModule.schemas`
with the value `[CUSTOM_ELEMENTS_SCHEMA]`.
E.g. for bootstrap:
```
bootstrap(MyComponent, {schemas: [CUSTOM_ELEMENTS_SCHEMA]});
```