Change a few more uses of the old try-catch syntax.

pkg/unittest/expect.dart

 // Copyright (c) 2012, 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.
 
 /**
  * This is the main assertion function. It asserts that [actual]
  * matches the [matcher]. [matcher] is optional and defaults to isTrue,
  * so expect can be used with a single predicate argument. [reason]
  * is optional and is typically not supplied if a reasonable matcher is
  * explicitly provided, as a reason can be generated from the matcher.
@@ skipping 23 matching lines @@
  *     [dart-matchers] https://github.com/Ladicek/dart-matchers
  */
 void expect(actual, [matcher = isTrue, String reason = null,
             FailureHandler failureHandler = null,
             bool verbose = false]) {
   matcher = wrapMatcher(matcher);
   bool doesMatch;
   var matchState = new MatchState();
   try {
     doesMatch = matcher.matches(actual, matchState);
-  } catch (var e, var trace) {
+  } catch (e, trace) {
     doesMatch = false;
     if (reason == null) {
       reason = '${(e is String) ? e : e.toString()} at $trace';
     }
   }
   if (!doesMatch) {
     if (failureHandler == null) {
       failureHandler = getOrCreateExpectFailureHandler();
     }
     failureHandler.failMatch(actual, matcher, reason, matchState, verbose);
@@ skipping 82 matching lines @@
  * formatter is returned; this allows custom expect handlers to easily
  * get a reference to the default formatter.
  */
 ErrorFormatter configureExpectFormatter([ErrorFormatter formatter = null]) {
   if (formatter == null) {
     formatter = _defaultErrorFormatter;
   }
   return _assertErrorFormatter = formatter;
 }