[BUGFIX beta] Allow ArrayProxy#pushObjects to accept ArrayProxy again

[nlfurniss]

This fixes #16621

@rwjblue and @hjdivad proposed the following solution:

• Drop the assertion in pushObjects entirely
• docs: Implementations have to assert their arguments in replace (which is the method implementations of MutableArray are expected to implement)

I'm don't know enough about Ember to know what #2 means, but would be happy to implement it once I understand what needs to be added to the docs.

[rwjblue]

Looks like the CI failures are related to the changes here...

[nlfurniss]

Weird, wonder why that didn't fail when i ran the tests locally...

What should I do with this failing test? Remove it?

[rwjblue]

Only the production build tests were failing because we are using assert.throws, however now we are no longer throw new Error() we rely on the replace implementation to do it and it does an Ember.assert (which is stripped in production builds).

tldr; s/assert.throws/expectAssertion/ in that file

[nlfurniss]

Added docs and travis ci passes 🎉

[hjdivad]

docs: Implementations have to assert their arguments in replace (which is the method implementations of MutableArray are expected to implement)

I'm don't know enough about Ember to know what #2 means, but would be happy to implement it once I understand what needs to be added to the docs.

It means updating the docs in MutableArray#replace to make clear that part of the MutableArray contract is that any type checking done in insertion is done specifically in replace.

As a bonus ArrayProxy#replace should probably refer to the MutableArray#replace docs.

[nlfurniss]

Travis failed due to disconnect, but last 2 runs were clean. Would re-run but dont have permission

[hjdivad]

i've restarted the job