Restructure the Kernel string table.

pkg/kernel/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 56 matching lines @@
     writeByte((value >> 16) & 0xFF);
     writeByte((value >> 8) & 0xFF);
     writeByte(value & 0xFF);
   }
 
   void writeUtf8Bytes(List<int> utf8Bytes) {
     writeUInt30(utf8Bytes.length);
     writeBytes(utf8Bytes);
   }
 
-  void writeStringTableEntry(String string) {
-    List<int> utf8Bytes = const Utf8Encoder().convert(string);
-    writeUInt30(utf8Bytes.length);
-    writeBytes(utf8Bytes);
-  }
-
   void writeStringTable(StringIndexer indexer) {
+    // Write the end offsets.
     writeUInt30(indexer.numberOfStrings);
+    int endOffset = 0;
     for (var entry in indexer.entries) {
-      writeStringTableEntry(entry.value);
+      endOffset += entry.utf8Bytes.length;
+      writeUInt30(endOffset);
+    }
+    // Write the UTF-8 encoded strings.
+    for (var entry in indexer.entries) {
+      writeBytes(entry.utf8Bytes);
     }
   }
 
   void writeStringReference(String string) {
     writeUInt30(_stringIndexer[string]);
   }
 
   void writeUriReference(String string) {
     int index = _sourceUriIndexer[string];
     if (index == null) {
@@ skipping 992 matching lines @@
 
   void exit(List<TypeParameter> typeParameters) {
     stackHeight -= typeParameters.length;
   }
 
   int operator [](TypeParameter parameter) => index[parameter];
 }
 
 class StringTableEntry implements Comparable<StringTableEntry> {
   final String value;
+  final List<int> utf8Bytes;
   int frequency = 0;
 
-  StringTableEntry(this.value);
+  StringTableEntry(String value)
+      : value = value,
+        utf8Bytes = const Utf8Encoder().convert(value);
 
   int compareTo(StringTableEntry other) => other.frequency - frequency;
 }
 
 class StringIndexer extends RecursiveVisitor<Null> {
   final List<StringTableEntry> entries = <StringTableEntry>[];
   final LinkedHashMap<String, int> index = new LinkedHashMap<String, int>();
 
   StringIndexer() {
     put('');
@@ skipping 192 matching lines @@
   void flush() {
     _sink.add(_buffer.sublist(0, length));
     _buffer = new Uint8List(SIZE);
     length = 0;
   }
 
   void flushAndDestroy() {
     _sink.add(_buffer.sublist(0, length));
   }
 }