fix(client): Fix stringify serializing objects

Serialize uses the name of the constructor to serialize objects.
When the object was created using Object.create(null) or has a property
constructor this may throw an Error

client/stringify.js

@@ -39,11 +39,16 @@ var stringify = function stringify(obj, depth) {
     } else if (obj.outerHTML) {
       return obj.outerHTML;
     } else {
-      strs.push(obj.constructor.name);
+      var constructor = 'Object';
+      if (obj.constructor && typeof obj.constructor === 'function') {
+        constructor = obj.constructor.name;
+      }
+
+      strs.push(constructor);
       strs.push('{');
       var first = true;
       for (var key in obj) {
-        if (obj.hasOwnProperty(key)) {
+        if (Object.prototype.hasOwnProperty.call(obj, key)) {
           if (first) {
             first = false;
           } else {

test/client/stringify.spec.js

@@ -32,6 +32,28 @@ describe('stringify', function() {
     expect(stringify(['a', 'b', null, true, false])).toBe("['a', 'b', null, true, false]");
   });
 
+  it('should serialize objects', function () {
+    var obj;
+
+
+    obj = {a: 'a', b: 'b', c: null, d: true, e: false};
+    expect(stringify(obj)).toBe('Object{a: \'a\', b: \'b\', c: null, d: true, e: false}');
+
+    function MyObj() {
+      this.a = 'a';
+    }
+
+    obj = new MyObj();
+    expect(stringify(obj)).toBe('MyObj{a: \'a\'}');
+
+    obj = {constructor: null};
+    expect(stringify(obj)).toBe('Object{constructor: null}');
+
+    obj = Object.create(null);
+    obj.a = 'a';
+    expect(stringify(obj)).toBe('Object{a: \'a\'}');
+  });
+
 
   it('should serialize html', function() {
     var div = document.createElement('div');