Disable the polyfill when the feature is available in ember-source

[Windvis]

Once the upstream PR is merged we know the version for which the polyfill needs to be disabled.

The polyfill should be removed from the final build of all projects that have this version and a warning should be shown in the console that the polyfill can be safely removed.

[musaffa]

Also consider moving it to ember-polyfills.

[Windvis]

@musaffa Yes, for sure! Once the PR is merged I will finish up this addon and ask around to get it moved to the ember-polyfill organisation.