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

tests/compiler/dart2js_native/native_class_inheritance1_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 interferes with
 // subsequent resolving the subclass's method.  This might happen if the
 // superclass caches the method in the prototype, so shadowing the dispatcher
 // stored on Object.prototype.
 
 // Version 1: It might be possible to call foo directly.
@@ skipping 65 matching lines @@
   var b2 = makeB2();
   Expect.equals(10000 + 99, a2.foo());
   Expect.equals(20000 + 1000, b2.foo());
 
   Expect.equals(10000 + 1, a2.foo(1));
   Expect.equals(20000 + 2, b2.foo(2));
 
   bool caught = false;
   try {
     a1.foo(20);
-  } catch (var ex) {
+  } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodException);
   }
   Expect.isTrue(caught, 'a1.foo(20) should throw');
 
   caught = false;
   try {
     var x = 123;
     x.foo(20);
-  } catch (var ex) {
+  } catch (ex) {
     caught = true;
     Expect.isTrue(ex is NoSuchMethodException);
   }
   Expect.isTrue(caught, "x.foo(20) should throw");
 }