src/vs/platform/contextkey/common/contextkey.ts/ContextKeyOrExpr/substituteConstants
class ContextKeyOrExpr:	public substituteConstants(): ContextKeyExpression | undefined {
		const exprArr = eliminateConstantsInArray(this.expr);
		if (exprArr === this.expr) {
			// no change
			return this;
		}
		return ContextKeyOrExpr.create(exprArr, this.negated, false);
	}