Update almost all tests (except co19) to use the new try-catch syntax.

tests/language/throw3_test.dart

 // Copyright (c) 2011, 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.
 // Dart test program for testing throw statement
 
 class MyException {
   const MyException([String message = ""]) : message_ = message;
   final String message_;
 }
 
 class Helper {
   static int f1(int i) {
     try {
       int j;
       i = 100;
       i = func();
       i = 200;
-    } catch (MyException exception) {
+    } on MyException catch (exception) {
       i = 50;
       print(exception.message_);
     } finally {
       i = i + 800;
     }
     return i;
   }
 
   static int func() {
     try {
       int i = 0;
       while (i < 10) {
         i++;
       }
       if (i > 0) {
         throw new MyException("Test for exception being thrown");
       }
-    } catch (MyException ex) {
+    } on MyException catch (ex) {
       print(ex.message_);
       throw;  // Rethrow the exception.
     }
     return 10;
   }
 }
 
 class Throw3Test {
   static testMain() {
     Expect.equals(850, Helper.f1(1));
   }
 }
 
 main() {
   Throw3Test.testMain();
 }