Add toJSON alias of valueOf. [closes #521]

lodash.js

@@ -3561,7 +3561,7 @@
      *
      * @name valueOf
      * @memberOf _
-     * @alias value
+     * @alias value, toJSON
      * @category Chaining
      * @returns {*} Returns the wrapped value.
      * @example
@@ -8427,6 +8427,7 @@
 
     // add "Chaining" functions to the wrapper
     lodash.prototype.chain = wrapperChain;
+    lodash.prototype.toJSON = wrapperValueOf;
     lodash.prototype.toString = wrapperToString;
     lodash.prototype.value = wrapperValueOf;
     lodash.prototype.valueOf = wrapperValueOf;

test/test.js

@@ -9659,6 +9659,17 @@
         skipTest();
       }
     });
+
+    test('should be aliased', 2, function() {
+      if (!isNpm) {
+        var expected = _.prototype.valueOf;
+        strictEqual(_.prototype.toJSON, expected);
+        strictEqual(_.prototype.value, expected);
+      }
+      else {
+        skipTest(2);
+      }
+    });
   }());
 
   /*--------------------------------------------------------------------------*/