promiseEffectOnlyPhases() {
        this.gate._hasNoEffect = false;
        this.gate._effectPermutesStates = false;
        this.gate._effectCreatesSuperpositions = false;
        this.gate._isDefinitelyUnitary = true;
        return this;
    }
Sets meta-properties to indicate the gate is safe for classical, quantum, and mixed use.
@returns {!GateBuilder}