Improve implementation of isInstanceOf in JSONSchemaValidator.

chrome/renderer/resources/extensions/json_schema.js

Index: chrome/renderer/resources/extensions/json_schema.js
diff --git a/chrome/renderer/resources/extensions/json_schema.js b/chrome/renderer/resources/extensions/json_schema.js
index 9b109bfb6bcd276c2d91f69db2b28663caed4e5e..df91335abf2bbb16f25a5c160aa6f04daebc9d82 100644
--- a/chrome/renderer/resources/extensions/json_schema.js
+++ b/chrome/renderer/resources/extensions/json_schema.js
@@ -280,27 +280,10 @@ chromeHidden.JSONSchemaValidator.prototype.validateObject = function(
   // If "instanceof" property is set, check that this object inherits from
   // the specified constructor (function).
   if (schema.isInstanceOf) {
-    var isInstance = function() {
-      var constructor = this[schema.isInstanceOf];
-      if (constructor) {
-        return (instance instanceof constructor);
-      }
-
-      // Special-case constructors that can not always be found on the global
-      // object, but for which we to allow validation.
-      var allowedNamedConstructors = {
-        "Window": true,
-        "ImageData": true
-      }
-      if (!allowedNamedConstructors[schema.isInstanceOf]) {
-        throw "Attempt to validate against an instance ctor that could not be" +
-              "found: " + schema.isInstanceOf;
-      }
-      return (schema.isInstanceOf == instance.constructor.name)
-    }();
-
-    if (!isInstance)
+    if (Object.prototype.toString.call(instance) !=

[arv (Not doing code reviews), 2012/03/05 19:13:07]

Maybe we should have walked the prototype chain so that we could have used
Window in the API. Using "global" seems ugly.

function isInstanceOfClass(object , className) {
  if (!object)
    return false;
  if (Object.prototype.toString.call(instance) === "[object " + className + "]")
    return true;
  return isInstanceOfClass(Object.getPrototypeOf(object), className);
}

[Aaron Boodman, 2012/03/05 21:06:08]

I agree the recursive search is cooler, but in this case, I actually think that
documenting the return type is "global" is more correct than "Window".

I'll send a review for the recursive search, but will leave the docs the same.

+        "[object " + schema.isInstanceOf + "]") {
       this.addError(propPath, "notInstance", [schema.isInstanceOf]);
+    }
   }
 
   // Exit early from additional property check if "type":"any" is defined.