Remove () from iterator

[lrytz]

Fixes scala/collection-strawman#520

[julienrf]

If this gets merged we should:

• update the FAQ to always write iterator (without parens),
• close Add an iterator() alias to iterator scala-collection-compat#7

[julienrf]

As mentioned here scala/collection-strawman#520 (comment), we should also remove the parens to the XxxFactory#newBuilder operation. And probably to IterableOps#newSpecificBuilder as well (though this one didn’t exist in 2.12, so it’s not a problem to keep the parens, but we should just use the same convention everywhere…)

[lrytz]

I just did that, just need to push the changes

[sjrd]

Because of the change in newBuilder especially, we'll need this PR to land (and a -pre- to be built from it) before we can finalize changes in Scala.js, so the sooner it gets merged, the likelier it gets that Scala.js can be ready (almost) in time for the release.

[sjrd]

@lrytz Hum for newBuilder, don't you also want to remove the () in IterableFactory.newBuilder[A]() and all its implementations?

Also MapFactory.newBuilder[K, V]().

[julienrf]

Good catch @sjrd. Indeed we should remove the () here too.

[lrytz]

I think I caught them all now. Also added a commit for ArrayBuilder.make.

[lrytz]

ArrayBuilder.make actually had () in 2.12, so this is a breaking change. https://github.com/scala/scala/blob/v2.12.6/src/library/scala/collection/mutable/ArrayBuilder.scala#L34

[szeiger]

I'm not a fan of adding another breaking change but it makes it consistent with the rest.