Implement correct scoping rules for variables.

sdk/lib/_internal/compiler/implementation/dart_backend/utils.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.
 
 part of dart_backend;
 
 class CloningVisitor implements Visitor<Node> {
   final TreeElements originalTreeElements;
   final TreeElementMapping cloneTreeElements;
 
   CloningVisitor(originalTreeElements)
       : cloneTreeElements =
             new TreeElementMapping(originalTreeElements.currentElement),
         this.originalTreeElements = originalTreeElements;
 
   visit(Node node) {
     if (node == null) return null;
     final clone = node.accept(this);
 
     final originalElement = originalTreeElements[node];
     if (originalElement != null) cloneTreeElements[clone] = originalElement;
 
     final originalType = originalTreeElements.getType(node);
     if (originalType != null) cloneTreeElements.setType(clone, originalType);
     return clone;
   }
 
-  visitBlock(Block node) => new Block(visit(node.statements));
+  visitBlock(Block node) {
+    return new Block(visit(node.statements), node.declarations);
+  }
 
   visitBreakStatement(BreakStatement node) => new BreakStatement(
       visit(node.target), node.keywordToken, node.semicolonToken);
 
   visitCascade(Cascade node) => new Cascade(visit(node.expression));
 
   visitCascadeReceiver(CascadeReceiver node) => new CascadeReceiver(
       visit(node.expression), node.cascadeOperator);
 
   visitCaseMatch(CaseMatch node) => new CaseMatch(
@@ skipping 141 matching lines @@
       new StringInterpolation(visit(node.string), visit(node.parts));
 
   visitStringInterpolationPart(StringInterpolationPart node) =>
       new StringInterpolationPart(visit(node.expression), visit(node.string));
 
   visitStringJuxtaposition(StringJuxtaposition node) =>
       new StringJuxtaposition(visit(node.first), visit(node.second));
 
   visitSwitchCase(SwitchCase node) => new SwitchCase(
       visit(node.labelsAndCases), node.defaultKeyword, visit(node.statements),
-      node.startToken);
+      node.startToken, node.declarations);
 
   visitSwitchStatement(SwitchStatement node) => new SwitchStatement(
       visit(node.parenthesizedExpression), visit(node.cases),
       node.switchKeyword);
 
   visitLiteralSymbol(LiteralSymbol node) => new LiteralSymbol(
       node.hashToken, visit(node.identifiers));
 
   visitThrow(Throw node) => new Throw(
       visit(node.expression), node.throwToken, node.endToken);
@@ skipping 83 matching lines @@
   }
 
   Node visitStringNode(StringNode node) {
     unimplemented('visitNode', node: node);
   }
 
   unimplemented(String message, {Node node}) {
     throw message;
   }
 }