Fix issue #5258 (#5259)

Sanitize serializer.data to remove hidden fields before rendering template JSON instance to raw data form.

* Fix lint issues

rest_framework/renderers.py

@@ -556,7 +556,10 @@ class BrowsableAPIRenderer(BaseRenderer):
                 accepted = self.accepted_media_type
                 context = self.renderer_context.copy()
                 context['indent'] = 4
-                content = renderer.render(serializer.data, accepted, context)
+                data = {k: v for (k, v) in serializer.data.items()
+                        if not isinstance(serializer.fields[k],
+                                          serializers.HiddenField)}
+                content = renderer.render(data, accepted, context)
             else:
                 content = None