[Fasta] include source code in dill

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';
 import 'tag.dart';
 
 class ParseError {
   String filename;
   int byteIndex;
   String message;
   String path;
@@ skipping 50 matching lines @@
     }
   }
 
   int readMagicWord() {
     return (readByte() << 24) |
         (readByte() << 16) |
         (readByte() << 8) |
         readByte();
   }
 
+  List<int> readUtf8Bytes() {
+    List<int> bytes = new Uint8List(readUInt());
+    bytes.setRange(0, bytes.length, _bytes, _byteIndex);
+    _byteIndex += bytes.length;
+    return bytes;
+  }
+
   String readStringEntry() {
     int numBytes = readUInt();
     // Utf8Decoder will skip leading BOM characters, but we must preserve them.
     // Collect leading BOMs before passing the bytes onto Utf8Decoder.
     int numByteOrderMarks = 0;
     while (_byteIndex + 2 < _bytes.length &&
         _bytes[_byteIndex] == 0xef &&
         _bytes[_byteIndex + 1] == 0xbb &&
         _bytes[_byteIndex + 2] == 0xbf) {
       ++numByteOrderMarks;
@@ skipping 177 matching lines @@
     var mainMethod = readMemberReference(allowNull: true);
     program.mainMethodName ??= mainMethod;
   }
 
   Map<String, Source> readUriToSource() {
     readSourceUriTable();
     int length = _sourceUriTable.length;
     Map<String, Source> uriToSource = <String, Source>{};
     for (int i = 0; i < length; ++i) {
       String uri = _sourceUriTable[i];
-      String sourceCode = readStringEntry();
+      List<int> sourceCode = readUtf8Bytes();
       int lineCount = readUInt();
       List<int> lineStarts = new List<int>(lineCount);
       int previousLineStart = 0;
       for (int j = 0; j < lineCount; ++j) {
         int lineStart = readUInt() + previousLineStart;
         lineStarts[j] = lineStart;
         previousLineStart = lineStart;
       }
       uriToSource[uri] = new Source(lineStarts, sourceCode);
     }
@@ skipping 815 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;
   }
 }