Add regression test

Author: ahejlsberg

tests/cases/compiler/typeArgumentDefaultUsesConstraintOnCircularDefault.ts

@@ -1,5 +1,11 @@
-type Test<T extends string = T> = { value: T };
+type Test<T extends string = T> = { value: T };  // Error
 
 let zz: Test = { foo: "abc" };  // should error on comparison with Test<string>
 
-let zzy: Test = { value: {} };  // should error
+let zzy: Test = { value: {} };
+
+// Simplified repro from #28873
+
+class C1<T extends C1 = any> {}
+
+class C2<T extends C2<any> = any> {}