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

tests/compiler/dart2js_native/native_class_inheritance3_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 to see if resolving a hidden native class's method to noSuchMethod
 // interferes with subsequent resolving of the method.  This might happen if the
 // noSuchMethod is cached on Object.prototype.
 
 class A1 native "*A1" {
 }
@@ skipping 71 matching lines @@
 
 
   expectNoSuchMethod(() => b1.foo(3), 'b1.foo(3)');
   expectNoSuchMethod(() => a1.foo(4), 'a1.foo(4)');
 }
 
 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);
 }