[kernel] Add fileOffset on FunctionExpression

pkg/kernel/lib/binary/ast_from_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_from_binary;
 
 import 'dart:convert';
 import 'dart:typed_data';
 
 import '../ast.dart';
 import '../transformations/flags.dart';
@@ skipping 908 matching lines @@
       case Tag.ConstMapLiteral:
         int offset = readOffset();
         var keyType = readDartType();
         var valueType = readDartType();
         return new MapLiteral(readMapEntryList(),
             keyType: keyType, valueType: valueType, isConst: true)
           ..fileOffset = offset;
       case Tag.AwaitExpression:
         return new AwaitExpression(readExpression());
       case Tag.FunctionExpression:
-        return new FunctionExpression(readFunctionNode());
+        int offset = readOffset();
+        return new FunctionExpression(readFunctionNode())..fileOffset = offset;
       case Tag.Let:
         var variable = readVariableDeclaration();
         int stackHeight = variableStack.length;
         pushVariableDeclaration(variable);
         var body = readExpression();
         variableStack.length = stackHeight;
         return new Let(variable, body);
       case Tag.VectorCreation:
         var length = readUInt();
         return new VectorCreation(length);
@@ skipping 336 matching lines @@
       ..fileOffset = offset
       ..fileEqualsOffset = fileEqualsOffset;
   }
 
   int readOffset() {
     // Offset is saved as unsigned,
     // but actually ranges from -1 and up (thus the -1)
     return readUInt() - 1;
   }
 }