Implement patch records to patch canonical objects.

tests/language/issue21079_test.dart

Index: tests/language/issue21079_test.dart
diff --git a/tests/language/issue21079_test.dart b/tests/language/issue21079_test.dart
new file mode 100644
index 0000000000000000000000000000000000000000..bf5c6a0610d9d2452e64444ab25f9baa1a800605
--- /dev/null
+++ b/tests/language/issue21079_test.dart
@@ -0,0 +1,13 @@
+import 'dart:mirrors';

[rmacnak, 2015/07/28 22:43:22]

Missing boilerplate header.

Needs to run as a script snapshot to test the issue.

+import 'dart:isolate';
+import "package:expect/expect.dart";
+
+void main() {
+  Expect.isTrue(reflectClass(MyException).superclass.reflectedType == IsolateSpawnException);
+
+  Expect.isTrue(reflectClass(IsolateSpawnException).reflectedType == IsolateSpawnException);
+}
+
+class MyException extends IsolateSpawnException {}
+
+