Updates the acceptance core tests to work with ES2015 devmode output.
There were two issues surfacing:
* The NodeJS test execution failed because Domino does not handle
destructuring syntax properly. This is because `Node.children` is not
an iterable.
* `forwardRef` does not work with ES2015 and TypeScript's decorator
downlevel emit. This is a known limitation we work around in Angular
applications by either compiling tests with the Angular compiler, or
by running a custom decorator downlevel transform (like in the CLI).
PR Close#44505
Paul Gschwendtner
807c6a4e10