code: static void addFeatureToScript(Node scriptNode, Feature feature) {
      checkState(scriptNode.isScript(), scriptNode);
      FeatureSet currentFeatures = getFeatureSetOfScript(scriptNode);
      FeatureSet newFeatures =
          currentFeatures != null
              ? currentFeatures.with(feature)
              : FeatureSet.BARE_MINIMUM.with(feature);
      scriptNode.putProp(Node.FEATURE_SET, newFeatures);
    }
docs: Adds the given features to a SCRIPT node's FeatureSet property.