Use external byte arrays for token stream, this moves the token stream out of the isolate heap. For…

vm/datastream.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_DATASTREAM_H_
 #define VM_DATASTREAM_H_
 
 #include "platform/assert.h"
 #include "platform/utils.h"
 #include "vm/allocation.h"
@@ skipping 57 matching lines @@
   void ReadBytes(uint8_t* addr, intptr_t len) {
     ASSERT((end_ - current_) >= len);
     memmove(addr, current_, len);
     current_ += len;
   }
 
   intptr_t ReadUnsigned() {
     return Read<intptr_t>(kEndUnsignedByteMarker);
   }
 
+  intptr_t Position() const { return current_ - buffer_; }
+
+  void SetPosition(intptr_t value) {
+    ASSERT((end_ - buffer_) > value);
+    current_ = buffer_ + value;
+  }
+
+  const uint8_t* AddressOfCurrentPosition() const {
+    return current_;
+  }
+
+  void Advance(intptr_t value) {
+    ASSERT((end_ - current_) > value);
+    current_ = current_ + value;
+  }
+
  private:
   template<typename T>
   T Read() {
     return Read<T>(kEndByteMarker);
   }
 
   template<typename T>
   T Read(uint8_t end_byte_marker) {
     uint8_t b = ReadByte();
     if (b > kMaxUnsignedDataPerByte) {
@@ skipping 143 matching lines @@
   uint8_t* current_;
   intptr_t current_size_;
   ReAlloc alloc_;
 
   DISALLOW_COPY_AND_ASSIGN(WriteStream);
 };
 
 }  // namespace dart
 
 #endif  // VM_DATASTREAM_H_