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

tests/language/exception_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.
 class ExceptionTest {
   static testMain() {
     int i = 0;
     try {
       throw "Hello";
-    } catch (String s) {
+    } on String catch (s) {
       print(s);
       i += 10;
     }
 
     try {
       throw "bye";
-    } catch (String s) {
+    } on String catch (s) {
       print(s);
       i += 10;
     }
     Expect.equals(20, i);
 
     bool correctCatch = false;
     try {
       // This throws NullPointerException.
       throw null;
-    } catch (String s) {
+    } on String catch (s) {
       correctCatch = false;
-    } catch (NullPointerException e) {
+    } on NullPointerException catch (e) {
       correctCatch = true;
-    } catch (var x) {
+    } catch (x) {
       correctCatch = false;
     }
     Expect.isTrue(correctCatch);
   }
 }
 
 main() {
   ExceptionTest.testMain();
 }