code: function ObjectToProtocolObject_(object, mirror_serializer) {
    var content = {};
    for (var key in object) {
      // Only consider string keys.
      if (typeof key == 'string') {
        // Format the value based on its type.
        var property_value_json = ValueToProtocolValue_(object[key],
                                                        mirror_serializer);
        // Add the property if relevant.
        if (!IS_UNDEFINED(property_value_json)) {
          content[key] = property_value_json;
        }
      }
    }
  
    return content;
  }
docs: Convert an Object to its debugger protocol representation. The representation
  may be serilized to a JSON object using JSON.stringify().
  This implementation simply runs through all string property names, converts
  each property value to a protocol value and adds the property to the result
  object. For type "object" the function will be called recursively. Note that
  circular structures will cause infinite recursion.
  @param {Object} object The object to format as protocol object.
  @param {MirrorSerializer} mirror_serializer The serializer to use if any
  mirror objects are encountered.
  @return {Object} Protocol object value.