Merge pull request #2519 from CodeFalling/fix-isnan-error-symbols

fix _.isNaN errors on symbols

Author: megawac

test/objects.js

@@ -844,6 +844,9 @@
     assert.notOk(_.isNaN(new Number(0)), 'wrapped 0 is not NaN');
     assert.ok(_.isNaN(NaN), 'but NaN is');
     assert.ok(_.isNaN(new Number(NaN)), 'wrapped NaN is still NaN');
+    if (typeof Symbol !== 'undefined'){
+      assert.notOk(_.isNaN(Symbol()), 'symbol is not NaN');
+    }
   });
 
   QUnit.test('isNull', function(assert) {

underscore.js

@@ -1320,7 +1320,7 @@
 
   // Is the given value `NaN`?
   _.isNaN = function(obj) {
-    return isNaN(obj) && _.isNumber(obj);
+    return _.isNumber(obj) && isNaN(obj);
   };
 
   // Is a given value a boolean?