Avoid excessive data copying for ExternalStreamingStream::SetBookmark.

src/scanner-character-streams.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_SCANNER_CHARACTER_STREAMS_H_
 #define V8_SCANNER_CHARACTER_STREAMS_H_
 
 #include "src/handles.h"
 #include "src/scanner.h"
 #include "src/vector.h"
@@ skipping 81 matching lines @@
  public:
   ExternalStreamingStream(ScriptCompiler::ExternalSourceStream* source_stream,
                           v8::ScriptCompiler::StreamedSource::Encoding encoding)
       : source_stream_(source_stream),
         encoding_(encoding),
         current_data_(NULL),
         current_data_offset_(0),
         current_data_length_(0),
         utf8_split_char_buffer_length_(0),
         bookmark_(0),
+        bookmark_data_is_from_current_data_(false),
+        bookmark_data_offset_(0),
         bookmark_utf8_split_char_buffer_length_(0) {}
 
   virtual ~ExternalStreamingStream() {
     delete[] current_data_;
     bookmark_buffer_.Dispose();
     bookmark_data_.Dispose();
   }
 
   size_t BufferSeekForward(size_t delta) override {
     // We never need to seek forward when streaming scripts. We only seek
@@ skipping 20 matching lines @@
   size_t current_data_length_;
   // For converting UTF-8 characters which are split across two data chunks.
   uint8_t utf8_split_char_buffer_[4];
   size_t utf8_split_char_buffer_length_;
 
   // Bookmark support. See comments in ExternalStreamingStream::SetBookmark
   // for additional details.
   size_t bookmark_;
   Vector<uint16_t> bookmark_buffer_;
   Vector<uint8_t> bookmark_data_;
+  bool bookmark_data_is_from_current_data_;
+  size_t bookmark_data_offset_;
   uint8_t bookmark_utf8_split_char_buffer_[4];
   size_t bookmark_utf8_split_char_buffer_length_;
 };
 
 
 // UTF16 buffer to read characters from an external string.
 class ExternalTwoByteStringUtf16CharacterStream: public Utf16CharacterStream {
  public:
   ExternalTwoByteStringUtf16CharacterStream(Handle<ExternalTwoByteString> data,
                                             int start_position,
@@ skipping 23 matching lines @@
 
  private:
   static const size_t kNoBookmark = -1;
 
   size_t bookmark_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_SCANNER_CHARACTER_STREAMS_H_