src/vs/base/parts/quickinput/browser/quickInputList.ts/QuickInputList/getCheckedCount
class QuickInputList:	getCheckedCount() {
		let count = 0;
		const elements = this.elements;
		for (let i = 0, n = elements.length; i < n; i++) {
			if (elements[i].checked) {
				count++;
			}
		}
		return count;
	}