Don't use Symbol.for if it's available.

[benlesh]

Given that Symbol.iterator === Symbol.for('iterator') is false, we don't need to use Symbol.for to get the observable symbol if it's available.

This relates to a comment here. And should resolve that issue.

[zenparsing]

The advantage of using Symbol.for is that otherwise we might run into cross-realm issues. For example, if you get an observable that comes from another iframe or something. Does anyone still program that way? : )

[benlesh]

The advantage of using Symbol.for is that otherwise we might run into cross-realm issues. For example, if you get an observable that comes from another iframe or something. Does anyone still program that way? : )

Unsure. I just know that it doesn't align with prior art. If there's a way to polyfill that we can...