Refine parameter type for assert.propertyVal().
@@ -307,7 +307,7 @@ assert.isUndefined = function(value, opt_message) {};
assert.isDefined = function(value, opt_message) {};
/**
- * @param {Object} object
+ * @param {?Object|undefined} object
* @param {string} property
* @param {*} value
* @param {string=} opt_message
