Remove BlockExpression from the Kernel language.

lib/binary/ast_to_binary.dart

 // Copyright (c) 2016, 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 kernel.ast_to_binary;
 
 import '../ast.dart';
 import '../import_table.dart';
 import 'tag.dart';
 import 'dart:convert';
 import 'dart:typed_data';
@@ skipping 662 matching lines @@
     writeByte(Tag.FunctionExpression);
     writeNode(node.function);
   }
 
   visitLet(Let node) {
     writeByte(Tag.Let);
     writeVariableDeclaration(node.variable);
     writeNode(node.body);
   }
 
-  visitBlockExpression(BlockExpression node) {
-    writeByte(Tag.BlockExpression);
-    writeNodeList(node.body.statements);
-    writeNode(node.value);
-  }
-
   writeStatementOrEmpty(Statement node) {
     if (node == null) {
       writeByte(Tag.EmptyStatement);
     } else {
       writeNode(node);
     }
   }
 
   visitInvalidStatement(InvalidStatement node) {
     writeByte(Tag.InvalidStatement);
@@ skipping 551 matching lines @@
   void flush() {
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }