Use named constants for the mask values used to narrow byte array values.

runtime/lib/byte_array.dart

 // 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.
 
 interface ByteArray extends List default _InternalByteArray {
   ByteArray(int length);
 
   int get length();
 
   int getInt8(int byteOffset);
@@ skipping 146 matching lines @@
   }
   
   List getRange(int start, int length) {
     if (length == 0) return [];
     Arrays.rangeCheck(this, start, length);
     ByteArray list = new ByteArray(length);
     list._setRange(0, length, this, start);
     return list;
   }
 
+  // Implementation
 
-  // Implementation
+  static final int _UINT8_MAX = (1 << 8) - 1;
+  static final int _UINT16_MAX = (1 << 16) - 1;
+  static final int _UINT32_MAX = (1 << 32) - 1;
+  static final int _UINT64_MAX = (1 << 64) - 1;
 
   int _toInt(int value, int mask) {
     int result = value & mask;
     return result > (mask >> 1) ? (result - mask) : result;
   }
 
   int _toInt8(int value) {
-    return _toInt(value, (1 << 8) - 1);  // TODO(cshapiro): use a named value
+    return _toInt(value, _UINT8_MAX);
   }
 
   int _toUint8(int value) {
-    return value & ((1 << 8) - 1);  // TODO(cshapiro): use a named value
+    return value & _UINT8_MAX;
   }
 
   int _toInt16(int value) {
-    return _toInt(value, (1 << 16) - 1);  // TODO(cshapiro): use a named value
+    return _toInt(value, _UINT16_MAX);
   }
 
   int _toUint16(int value) {
-    return value & ((1 << 16) - 1);  // TODO(cshapiro): use a named value
+    return value & _UINT16_MAX;
   }
 
   int _toInt32(int value) {
-    return _toInt(value, (1 << 32) - 1);  // TODO(cshapiro): use a named value
+    return _toInt(value, _UINT32_MAX);
   }
 
   int _toUint32(int value) {
-    return value & ((1 << 32) - 1);  // TODO(cshapiro): use a named value
+    return value & _UINT32_MAX;
   }
 
   int _toInt64(int value) {
-    return _toInt(value, (1 << 64) - 1);  // TODO(cshapiro): use a named value
+    return _toInt(value, _UINT64_MAX);
   }
 
   int _toUint64(int value) {
-    return value & ((1 << 64) - 1);  // TODO(cshapiro): use a named value
+    return value & _UINT64_MAX;
   }
 
   int _length() native "ByteArray_getLength";
 
   void _setRange(int start, int length, ByteArray from, int startFrom)
       native "ByteArray_setRange";
 }
 
 
 class _ByteArrayIterator implements Iterator {
@@ skipping 329 matching lines @@
 
   void _setFloat32(int byteOffset, double value)
     native "ExternalByteArray_setFloat32";
 
   double _getFloat64(int byteOffset)
     native "ExternalByteArray_getFloat64";
 
   void _setFloat64(int byteOffset, double value)
     native "ExternalByteArray_setFloat64";
 }