defaultValue check for null

CHANGES.md

@@ -28,6 +28,7 @@ Change Log
 * Added a Sandcastle demo for setting time with the Clock API [#5457](https://github.com/AnalyticalGraphicsInc/cesium/pull/5457);
 * Added support for `ParticleSystem`s. [#5212](https://github.com/AnalyticalGraphicsInc/cesium/pull/5212)
 * Added `Cesium.Math.randomBetween`.
+* `defaultValue` updated to check for Null.
 
 ### 1.34 - 2017-06-01
 

Source/Core/defaultValue.js

@@ -19,7 +19,7 @@ define([
      * param = Cesium.defaultValue(param, 'default');
      */
     function defaultValue(a, b) {
-        if (a !== undefined) {
+        if (a !== undefined && a !== null) {
             return a;
         }
         return b;

Specs/Core/defaultValueSpec.js

@@ -0,0 +1,26 @@
+/*global defineSuite*/
+defineSuite([
+        'Core/defaultValue'
+    ], function(
+        defaultValue) {
+    'use strict';
+
+    it('Works with first parameter undefined', function() {
+        expect(function(){
+            defaultValue.defaultValue(undefined, 5);
+        }).toEqual(5);
+    });
+
+    it('Works with first parameter null', function() {
+        expect(function(){
+            defaultValue.defaultValue(null, 5);
+        }).toEqual(5);
+    });
+
+    it('Works with first parameter not undefined and not null', function() {
+        expect(function(){
+            defaultValue.defaultValue(1, 5);
+        }).toEqual(1);
+    });
+
+});