Consider multi in add/remove/toggle select logic

src/ol/interaction/selectinteraction.js

@@ -320,6 +320,7 @@ ol.interaction.Select.handleEvent = function(mapBrowserEvent) {
         /**
          * @param {ol.Feature|ol.render.Feature} feature Feature.
          * @param {ol.layer.Layer} layer Layer.
+         * @return {boolean|undefined} Continue to iterate over the features.
          */
         function(feature, layer) {
           if (this.filter_(feature, layer)) {
@@ -332,6 +333,7 @@ ol.interaction.Select.handleEvent = function(mapBrowserEvent) {
               deselected.push(feature);
               this.removeFeatureLayerAssociation_(feature);
             }
+            return !this.multi_;
           }
         }, this, this.layerFilter_);
     var i;