Support for new catch syntax in dart2js

dart/lib/compiler/implementation/scanner/parser.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.
 
 /**
  * An event generating parser of Dart programs. This parser expects
  * all tokens in a linked list (aka a token stream).
  *
  * The class [Scanner] is used to generate a token stream. See the
  * file scanner.dart.
@@ skipping 1561 matching lines @@
       return expectSemicolon(token);
     }
   }
 
   Token parseTryStatement(Token token) {
     assert(optional('try', token));
     Token tryKeyword = token;
     listener.beginTryStatement(tryKeyword);
     token = parseBlock(token.next);
     int catchCount = 0;
-    while (optional('catch', token)) {
-      Token catchKeyword = token;
-      // TODO(ahe): Validate the "parameters".
-      token = parseFormalParameters(token.next);
+
+    String value = token.stringValue;
+    while (value === 'catch' || value === 'on') {
+      var onKeyword = null;
+      if (value === 'on') {
+        // on qualified catchPart?
+        onKeyword = token;
+        token = parseType(token.next);
+        value = token.stringValue;
+      }
+      Token catchKeyword = null;
+      if (value === 'catch') {
+        catchKeyword = token;
+        // TODO(ahe): Validate the "parameters".
+        token = parseFormalParameters(token.next);
+      }
       token = parseBlock(token);
       ++catchCount;
-      listener.handleCatchBlock(catchKeyword);
+      listener.handleCatchBlock(onKeyword, catchKeyword);
+      value = token.stringValue; // while condition
     }
+
     Token finallyKeyword = null;
     if (optional('finally', token)) {
       finallyKeyword = token;
       token = parseBlock(token.next);
       listener.handleFinallyBlock(finallyKeyword);
     }
     listener.endTryStatement(catchCount, tryKeyword, finallyKeyword);
     return token;
   }
 
@@ skipping 121 matching lines @@
     }
     listener.handleContinueStatement(hasTarget, continueKeyword, token);
     return expectSemicolon(token);
   }
 
   Token parseEmptyStatement(Token token) {
     listener.handleEmptyStatement(token);
     return expectSemicolon(token);
   }
 }