src/vs/platform/keybinding/common/keybindingResolver.ts/KeybindingResolver/whenIsEntirelyIncluded
class KeybindingResolver:	public static whenIsEntirelyIncluded(a: ContextKeyExpression | null | undefined, b: ContextKeyExpression | null | undefined): boolean {
		if (!b || b.type === ContextKeyExprType.True) {
			return true;
		}
		if (!a || a.type === ContextKeyExprType.True) {
			return false;
		}

		return this._implies(a, b);
	}