feat(perf): debounce resize callback

- The resize event fires often, so debouncing the function execution can
  improve performance dramatically

src/uiSelectController.js

@@ -5,8 +5,8 @@
  * put as much logic in the controller (instead of the link functions) as possible so it can be easily tested.
  */
 uis.controller('uiSelectCtrl',
-  ['$scope', '$element', '$timeout', '$filter', 'uisRepeatParser', 'uiSelectMinErr', 'uiSelectConfig', '$parse', '$injector', '$window',
-  function($scope, $element, $timeout, $filter, RepeatParser, uiSelectMinErr, uiSelectConfig, $parse, $injector, $window) {
+  ['$scope', '$element', '$timeout', '$filter', '$$uisDebounce', 'uisRepeatParser', 'uiSelectMinErr', 'uiSelectConfig', '$parse', '$injector', '$window',
+  function($scope, $element, $timeout, $filter, $$uisDebounce, RepeatParser, uiSelectMinErr, uiSelectConfig, $parse, $injector, $window) {
 
   var ctrl = this;
 
@@ -635,8 +635,8 @@ uis.controller('uiSelectCtrl',
     ctrl.searchInput.off('keyup keydown tagged blur paste');
   });
 
-  angular.element($window).bind('resize', function() {
+  angular.element($window).bind('resize', $$uisDebounce(function() {
     ctrl.sizeSearchInput();
-  });
+  }), 50);
 
 }]);

src/uisDebounceService.js

@@ -0,0 +1,24 @@
+/**
+ * Debounces functions
+ *
+ * Taken from UI Bootstrap $$debounce source code
+ * See https://github.com/angular-ui/bootstrap/blob/master/src/debounce/debounce.js
+ *
+ */
+uis.factory('$$uisDebounce', ['$timeout', function($timeout) {
+  return function(callback, debounceTime) {
+    var timeoutPromise;
+
+    return function() {
+      var self = this;
+      var args = Array.prototype.slice.call(arguments);
+      if (timeoutPromise) {
+        $timeout.cancel(timeoutPromise);
+      }
+
+      timeoutPromise = $timeout(function() {
+        callback.apply(self, args);
+      }, debounceTime);
+    };
+  };
+}]);