Change core lib, dart2js, and more for new optional parameters syntax

tests/corelib/collection_to_string_test.dart

Index: tests/corelib/collection_to_string_test.dart
===================================================================
--- tests/corelib/collection_to_string_test.dart	(revision 13683)
+++ tests/corelib/collection_to_string_test.dart	(working copy)
@@ -115,7 +115,7 @@
  * If exact is true, the returned collections will not be, and will not contain
  * a collection with ill-defined iteration order (i.e., a HashSet or HashMap).
  */
-Object randomCollection(int size, StringBuffer stringRep, [bool exact]) {
+Object randomCollection(int size, StringBuffer stringRep, {bool exact}) {
   return randomCollectionHelper(size, exact, stringRep, []);
 }