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

tests/language/throw2_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
 
 interface TestException {
   String getMessage();
 }
 
 class MyException implements TestException {
@@ skipping 12 matching lines @@
   const MyException3([String message = ""]) : message_ = message;
   String getMessage() { return message_; }
   final String message_;
 }
 
 class Helper {
   static int f1(int i) {
     try {
       int j;
       j = func();
-    } catch (MyException3 exception) {
+    } on MyException3 catch (exception) {
       i = 100;
       print(exception.getMessage());
-    } catch (MyException2 exception) {
+    } on MyException2 catch (exception) {
       try {
         i = func2();
         i = 200;
-      } catch (TestException exception) {
+      } on TestException catch (exception) {
         i = 50;
       }
       print(exception.getMessage());
-    } catch (MyException exception) {
+    } on MyException catch (exception) {
       i = func2();
       print(exception.getMessage());
     } finally {
       i = i + 800;
     }
     return i;
   }
 
   static int func() {
     int i = 0;
@@ skipping 20 matching lines @@
 
 class Throw2Test {
   static testMain() {
     Expect.equals(850, Helper.f1(1));
   }
 }
 
 main() {
   Throw2Test.testMain();
 }