src/vs/editor/browser/widget/diffEditorWidget.ts/DiffEditorWidget/_equals
class DiffEditorWidget:	private static _equals(a: URI | null, b: URI | null): boolean {
		if (!a && !b) {
			return true;
		}
		if (!a || !b) {
			return false;
		}
		return (a.toString() === b.toString());
	}