use findIndex instead of indexOf when looking up activeIndex (includes findIndex polyfill)

Author: plong0

src/uiSelectController.js

@@ -66,7 +66,9 @@ uis.controller('uiSelectCtrl',
       ctrl.search = EMPTY_SEARCH;
       //reset activeIndex
       if (ctrl.selected && ctrl.items.length && !ctrl.multiple) {
-        ctrl.activeIndex = ctrl.items.indexOf(ctrl.selected);
+        ctrl.activeIndex = ctrl.items.findIndex(function(item){
+          return angular.equals(this, item);
+        }, ctrl.selected);
       }
     }
   }
@@ -259,7 +261,7 @@ uis.controller('uiSelectCtrl',
       return false;
     }
     var itemIndex = ctrl.items.indexOf(itemScope[ctrl.itemProperty]);
-    var isActive =  itemIndex === ctrl.activeIndex;
+    var isActive =  itemIndex == ctrl.activeIndex;
 
     if ( !isActive || ( itemIndex < 0 && ctrl.taggingLabel !== false ) ||( itemIndex < 0 && ctrl.taggingLabel === false) ) {
       return false;
@@ -573,3 +575,27 @@ uis.controller('uiSelectCtrl',
   });
 
 }]);
+
+// Array findIndex polyfill (source: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/findIndex#Polyfill)
+if (!Array.prototype.findIndex) {
+  Array.prototype.findIndex = function(predicate) {
+    if (this === null) {
+      throw new TypeError('Array.prototype.findIndex called on null or undefined');
+    }
+    if (typeof predicate !== 'function') {
+      throw new TypeError('predicate must be a function');
+    }
+    var list = Object(this);
+    var length = list.length >>> 0;
+    var thisArg = arguments[1];
+    var value;
+
+    for (var i = 0; i < length; i++) {
+      value = list[i];
+      if (predicate.call(thisArg, value, i, list)) {
+        return i;
+      }
+    }
+    return -1;
+  };
+}