Fix leak of tokens during development builds

[bendemboski]

The logic for choosing between the Map and WeakMap for completed operation tracking wasn't right, and the result was that everything was being added to the Map, leaking every token. For waitForPromise() the token is the promise itself, meaning the resolved values were also leaking, which can easily add up to a memory leak of epic proportions.

[bendemboski]

I guess waitFor() on a coroutine is also extremely leaky since the token is the generator function itself, so its context probably includes this, meaning it will leak the containing object.

[scalvert]

Woah, thanks for finding this, @bendemboski. I'll take a look.

[scalvert]

Derp, so we'd essentially reversed the logic for token storage. Nice catch!

[rwjblue]

Can you make this mistake harder to make?

I'm thinking something like:

Suggested change

	return token === null || (type !== 'function' && type !== 'object')
	let isFunction = type === 'function';
	let isObject = token !== null && type === 'object';
	return isFunction || isObject

[bendemboski]

Sure, how about

    let isFunction = type === 'function';
    let isObject = token !== null && type === 'object';
    let isPrimitive = !isFunction && !isObject;

    return isPrimitive ? this.completedOperationsForPrimitives : this.completedOperationsForTokens;

[rwjblue]

Ya, seems great to me!

[scalvert]

I like.