fix(select): use strict compare when removing option from ctrl

Otherwise, if the removed option was the empty option (value ''),
and the currently selected option had a value of 0, the select
would think that the currently selected option had been removed,
causing the unknown option to be added again.

Fixes angular#9714
Fixes angular#10115
Closes angular#10203

Author: Narretz

src/ng/directive/select.js

@@ -209,10 +209,10 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
       };
 
 
-      self.removeOption = function(value, anySelected) {
+      self.removeOption = function(value) {
         if (this.hasOption(value)) {
           delete optionsMap[value];
-          if (ngModelCtrl.$viewValue == value && !anySelected) {
+          if (ngModelCtrl.$viewValue === value) {
             this.renderUnknownOption(value);
           }
         }
@@ -683,7 +683,7 @@ var selectDirective = ['$compile', '$parse', function($compile,   $parse) {
               if (count > 0) {
                 selectCtrl.addOption(label);
               } else if (count < 0) {
-                selectCtrl.removeOption(label, anySelected);
+                selectCtrl.removeOption(label);
               }
             });
           }

test/ng/directive/selectSpec.js

@@ -233,30 +233,31 @@ describe('select', function() {
         expect(scope.robot).toBe('');
       });
 
-      it('should not add the empty string when an option is selected and options are set in a timeout', inject(function($timeout) {
+      it('should not be set when an option is selected and options are set asynchronously',
+        inject(function($timeout) {
+          compile('<select ng-model="model" ng-options="opt.id as opt.label for opt in options">' +
+                      '</select>');
 
-        compile('<select ng-model="simpleModel" ng-options="opt.id as opt.label for opt in simpleOpts">' +
-                    '</select>');
-
-        scope.$apply(function() {
-          scope.simpleModel = 0;
-        });
+          scope.$apply(function() {
+            scope.model = 0;
+          });
 
-        $timeout(function() {
-          scope.simpleOpts = [
-            {id: 0, label: 'x'},
-            {id: 1, label: 'y'}
-          ];
-        }, 0);
+          $timeout(function() {
+            scope.options = [
+              {id: 0, label: 'x'},
+              {id: 1, label: 'y'}
+            ];
+          }, 0);
 
-        $timeout.flush();
+          $timeout.flush();
 
-        var options = element.find('option');
+          var options = element.find('option');
 
-        expect(options.length).toEqual(2);
-        expect(options.eq(0)).toEqualOption('0', 'x');
-        expect(options.eq(1)).toEqualOption('1', 'y');
-      }));
+          expect(options.length).toEqual(2);
+          expect(options.eq(0)).toEqualOption('0', 'x');
+          expect(options.eq(1)).toEqualOption('1', 'y');
+        })
+      );
 
       describe('interactions with repeated options', function() {