Rename RuntimeError to CyclicIntializationError, as per spec.

tests/language/lazy_static3_test.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 import "package:expect/expect.dart";
 
 final x = foo();
 var x2 = foo2();
 var x3 = foo3();
 var x4 = foo4();
@@ skipping 27 matching lines @@
   return fib(x - 1) + fib(x - 2);
 }
 
 main() {
   Expect.throws(() => fib(x), (e) => e == "interrupt initialization");
   Expect.equals(null, x);
 
   Expect.throws(() => fib(x2), (e) => e == "interrupt initialization");
   Expect.equals(499, x2);
 
-  Expect.throws(() => fib(x3), (e) => e is RuntimeError);
+  Expect.throws(() => fib(x3), (e) => e is CyclicInitializationError);
   Expect.equals(null, x3);
 
   Expect.equals(499, x4);
 
   Expect.equals(null, x5);
 
   Expect.equals(499, x6);
 
-  Expect.throws(() => fib(x7), (e) => e is RuntimeError);
+  Expect.throws(() => fib(x7), (e) => e is CyclicInitializationError);
 }