dart2dart: Implementation of simple try/catch.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.dart

 // Copyright (c) 2014, 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.
 
 library tree_ir_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 import 'optimization/optimization.dart';
@@ skipping 123 matching lines @@
     _addBlock(bodyBlock);
     visitStatement(node.body);
 
     _addBlock(nextBlock);
     visitStatement(node.next);
 
     ifTargets[node.body] = bodyBlock;
     ifTargets[node.next] = nextBlock;
   }
 
+  visitTry(Try node) {
+    // It's not obvious how we want to represent try statements here.
+    // TODO(kmillikin).
+  }
+
   visitExpressionStatement(ExpressionStatement node) {
     _addStatement(node);
     visitStatement(node.next);
   }
 
   visitFunctionDeclaration(FunctionDeclaration node) {
     _addStatement(node);
     visitStatement(node.next);
   }
 
@@ skipping 114 matching lines @@
   }
 
   visitWhileCondition(WhileCondition node) {
     String bodyTarget = collector.ifTargets[node.body].name;
     String nextTarget = collector.ifTargets[node.next].name;
     printStatement(null, "while ${expr(node.condition)}");
     printStatement(null, "do $bodyTarget");
     printStatement(null, "then $nextTarget" );
   }
 
+  visitTry(Try node) {
+    // It's not obvious how we want to represent try statements here.
+    // TODO(kmillikin).
+  }
+
   visitExpressionStatement(ExpressionStatement node) {
     printStatement(null, expr(node.expression));
   }
 
   visitFunctionDeclaration(FunctionDeclaration node) {
     printStatement(null, 'function ${node.definition.element.name}');
   }
 
   visitSetField(SetField node) {
     String object = expr(node.object);
@@ skipping 186 matching lines @@
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }