fix(select): don't call $render twice if $viewValue ref changes

Credits to @tepez for the fix

Closes angular#11329
Closes angular#11412

Author: Narretz

src/ng/directive/select.js

@@ -141,7 +141,6 @@ var SelectController =
  *
  */
 var selectDirective = function() {
-  var lastView;
 
   return {
     restrict: 'E',
@@ -200,11 +199,13 @@ var selectDirective = function() {
 
         // we have to do it on each watch since ngModel watches reference, but
         // we need to work of an array, so we need to see if anything was inserted/removed
+        var lastView, lastViewRef = NaN;
         scope.$watch(function selectMultipleWatch() {
-          if (!equals(lastView, ngModelCtrl.$viewValue)) {
+          if (lastViewRef === ngModelCtrl.$viewValue && !equals(lastView, ngModelCtrl.$viewValue)) {
             lastView = shallowCopy(ngModelCtrl.$viewValue);
             ngModelCtrl.$render();
           }
+          lastViewRef = ngModelCtrl.$viewValue;
         });
 
         // If we are a multiple select then value is now a collection

test/ng/directive/selectSpec.js

@@ -841,6 +841,60 @@ describe('select', function() {
       expect(element).toBeDirty();
     });
 
+
+    describe('calls to $render', function() {
+
+      var ngModelCtrl;
+
+      beforeEach(function() {
+        compile(
+          '<select name="select" ng-model="selection" multiple>' +
+          '<option>A</option>' +
+          '<option>B</option>' +
+          '</select>');
+
+        ngModelCtrl = element.controller('ngModel');
+        spyOn(ngModelCtrl, '$render').andCallThrough();
+      });
+
+
+      it('should call $render once when the reference to the viewValue changes', function() {
+        scope.$apply(function() {
+          scope.selection = ['A'];
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(1);
+
+        scope.$apply(function() {
+          scope.selection = ['A', 'B'];
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(2);
+
+        scope.$apply(function() {
+          scope.selection = [];
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(3);
+      });
+
+
+      it('should call $render once when the viewValue deep-changes', function() {
+        scope.$apply(function() {
+          scope.selection = ['A'];
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(1);
+
+        scope.$apply(function() {
+          scope.selection.push('B');
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(2);
+
+        scope.$apply(function() {
+          scope.selection.length = 0;
+        });
+        expect(ngModelCtrl.$render.calls.length).toBe(3);
+      });
+
+    });
+
   });