Merge branch 'add_toBeNullish' of https://github.com/MattMcCherry/jasmine

* Merges #2045 from @MattMcCherry

lib/jasmine-core/jasmine.js

@@ -150,6 +150,7 @@ getJasmineRequireObj().requireMatchers = function(jRequire, j$) {
       'toBeTrue',
       'toBeTruthy',
       'toBeUndefined',
+      'toBeNullish',
       'toContain',
       'toEqual',
       'toHaveSize',
@@ -6011,6 +6012,28 @@ getJasmineRequireObj().toBeNull = function() {
   return toBeNull;
 };
 
+getJasmineRequireObj().toBeNullish = function() {
+  /**
+   * {@link expect} the actual value to be `null` or `undefined`.
+   * @function
+   * @name matchers#toBeNullish
+   * @since 5.6.0
+   * @example
+   * expect(result).toBeNullish():
+   */
+  function toBeNullish() {
+    return {
+      compare: function(actual) {
+        return {
+          pass: null === actual || void 0 === actual
+        };
+      }
+    };
+  }
+
+  return toBeNullish;
+};
+
 getJasmineRequireObj().toBePositiveInfinity = function(j$) {
   /**
    * {@link expect} the actual value to be `Infinity` (infinity).