Test {{in-element}} instead of deprecated {{-in-element}}

[mydea]

This leads to failing tests on Canary, where {{-in-element}} is removed.

This updates the test to test the {{in-element}} helper on ember versions upwards of 3.20. I did not include an alternate branch to test {{-in-element}} on older versions because I figured that is kind of repetitive and we can assume they work the same.

[mydea]

Canary tests will fail because of:
#1066

[simonihmig]

Canary tests will fail because of:

Actually 3.8 is failing. Probably because the error is thrown at build-time by the AST transform (which is not taking your if-clause into account), at least that's what I would assume. Maybe adding https://github.com/ember-polyfills/ember-in-element-polyfill as a devDependency instead of the Ember version check would help?

[mydea]

Hmm, interesting! I changed the test to just always run and use {{in-element}} and installed ember-in-element-polyfill as dev dependency. Should hopefully work now 😅