Implement try/catch without finally, and without type checks.

frog/leg/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
 }
 
 class TreeElementMapping implements TreeElements {
@@ skipping 838 matching lines @@
 
   visitNamedArgument(NamedArgument node) {
     visit(node.expression);
   }
 
   visitSwitchStatement(SwitchStatement node) {
     unimplemented(node, 'switch');
   }
 
   visitTryStatement(TryStatement node) {
-    unimplemented(node, 'try');
+    visit(node.tryBlock);
+    if (node.catchBlocks.isEmpty() && node.finallyBlock == null) {
+      // TODO(ngeoffray): The precise location is
+      // node.getEndtoken.next. Adjust when issue #1581 is fixed.
+      error(node, MessageKind.NO_CATCH_NOR_FINALLY);
+    }
+    visit(node.catchBlocks);
+    visit(node.finallyBlock);
   }
 
   visitCatchBlock(CatchBlock node) {
-    unimplemented(node, 'catch');
+    Scope scope = new BlockScope(context);
+    if (node.formals.isEmpty()) {
+      error(node, MessageKind.EMPTY_CATCH_DECLARATION);
+    } else if (!node.formals.nodes.tail.isEmpty()
+               && !node.formals.nodes.tail.tail.isEmpty()) {
+      for (Node extra in node.formals.nodes.tail.tail) {
+        error(extra, MessageKind.EXTRA_CATCH_DECLARATION);
+      }
+    }
+    visitIn(node.formals, scope);
+    visitIn(node.block, scope);
   }
 
   visitTypedef(Typedef node) {
     unimplemented(node, 'typedef');
   }
 }
 
 class ClassResolverVisitor extends CommonResolverVisitor<Type> {
   Scope context;
 
@@ skipping 273 matching lines @@
 class TopScope extends Scope {
   LibraryElement get library() => element;
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) => library.find(name);
 
   Element add(Element element) {
     throw "Cannot add an element in the top scope";
   }
 }