alternative take on type projections

[jiripudil]

No description provided.

[ondrejmirtes]

I think this is totally OK when traversing. We have === logic in many places:

	public function traverse(callable $cb): Type
	{
		$keyType = $cb($this->keyType);
		$itemType = $cb($this->itemType);

		if ($keyType !== $this->keyType || $itemType !== $this->itemType) {
			if ($keyType instanceof NeverType && $itemType instanceof NeverType) {
				return new ConstantArrayType([], []);
			}

			return new self($keyType, $itemType);
		}

		return $this;
	}