Regression in global property lookup

[sholladay]

PR #153 was intended to make it easier to mock globals that Ky relies on.

But it actually broke my app's mocking...

In fact, in environments that have globalThis (including Node.js), the logic for determining which global object to use is completely broken. It will always choose globalThis no matter what. Anyone using an artificial window or self (e.g. with jsdom), which is necessary in React projects, is no longer able to put things there and have Ky pick up on them. They just get ignored.

This is happening because the return statements were removed from here. Instead, the if statements now "fall through" here until it hits globalThis, which doesn't have the same properties as window in my case, yet Ky chooses to use globalThis anyway, even though the property doesn't exist there.

Another consequence of falling through like this, even if your environment doesn't have globalThis, is that the order of precedence is reversed from what it was previously. Before it would stop at the earliest match found, now it stops at the last match found.

I would prefer to revert this commit and rethink how it works, but a simple temporary fix for the first problem would be to check that the property exists on globalThis before setting the parent to globalThis.

// cc @luxferresum