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

tests/html/hidden_dom_1_test.dart

 #library('HiddenDom1Test');
 #import('../../pkg/unittest/unittest.dart');
 #import('../../pkg/unittest/html_config.dart');
 #import('dart:html');
 
 // Test that the dart:html API does not leak native jsdom methods:
 //   onfocus setter.
 
 main() {
   useHtmlConfiguration();
@@ skipping 17 matching lines @@
 
 confuse(x) => opaqueTrue() ? x : (opaqueTrue() ? new Object() : new Decoy());
 
 /** Returns [:true:], but in a way that confuses the compiler. */
 opaqueTrue() => true;  // Expand as needed.
 
 checkNoSuchMethod(action()) {
   var ex = null;
   try {
     action();
-  } catch (var e) {
+  } catch (e) {
     ex = e;
   }
   if (ex === null)
     Expect.fail('Action should have thrown exception');
 
   Expect.isTrue(ex is NoSuchMethodException, 'ex is NoSuchMethodException');
 }