Update comment describing the length field in class Bigint.

vm/raw_object.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_RAW_OBJECT_H_
 #define VM_RAW_OBJECT_H_
 
 #include "platform/assert.h"
 #include "vm/globals.h"
 #include "vm/token.h"
@@ skipping 878 matching lines @@
 
   int64_t value_;
 
   friend class SnapshotReader;
 };
 
 
 class RawBigint : public RawInteger {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Bigint);
 
-  // Actual length at the time of allocation (later we may clamp the
-  // operational length but we need to maintain a consistent object
-  // length so that the object can be traversed during GC).
+  // Actual length in chunks at the time of allocation (later we may
+  // clamp the operational length but we need to maintain a consistent
+  // object length so that the object can be traversed during GC).
   intptr_t allocated_length_;
 
-  // Operation length of the bigint object, clamping can cause this length
-  // to be reduced. If the signed_length_ is negative then the number
-  // is negative.
+  // Operational length in chunks of the bigint object, clamping can
+  // cause this length to be reduced. If the signed_length_ is
+  // negative then the number is negative.
   intptr_t signed_length_;
 
   // A sequence of Chunks (typedef in Bignum) representing bignum digits.
   // Bignum::Chunk chunks_[Utils::Abs(signed_length_)];
   uint8_t data_[0];
 };
 
 
 class RawDouble : public RawNumber {
   RAW_HEAP_OBJECT_IMPLEMENTATION(Double);
@@ skipping 247 matching lines @@
   intptr_t type_;  // Uninitialized, simple or complex.
   intptr_t flags_;  // Represents global/local, case insensitive, multiline.
 
   // Variable length data follows here.
   uint8_t data_[0];
 };
 
 }  // namespace dart
 
 #endif  // VM_RAW_OBJECT_H_