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

tests/compiler/dart2js_native/native_method_rename1_frog_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.
 
 // Test the feature where the native string declares the native method's name.
 
 class A native "*A" {
   int foo() native 'fooA';
   int bar() native 'barA';
   int baz() native 'bazA';
@@ skipping 45 matching lines @@
 main() {
   setup();
   testDynamic();
   testTyped();
 }
 
 expectNoSuchMethod(action, note) {
   bool caught = false;
   try {
     action();
-  } catch (var ex) {
+  } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodException, note);
   }
   Expect.isTrue(caught, note);
 }