Make "as" a built-in identifier aka pseudo keyword

runtime/vm/intermediate_language.h

 // Copyright (c) 2013, 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_INTERMEDIATE_LANGUAGE_H_
 #define VM_INTERMEDIATE_LANGUAGE_H_
 
 #include "vm/allocation.h"
 #include "vm/ast.h"
 #include "vm/growable_array.h"
@@ skipping 51 matching lines @@
   V(_TypedList, _setFloat32, ByteArrayBaseSetFloat32, 756330666)               \
   V(_TypedList, _setFloat64, ByteArrayBaseSetFloat64, 1495546688)              \
   V(_TypedList, _setFloat32x4, ByteArrayBaseSetFloat32x4, 560495357)           \
   V(_GrowableObjectArray, get:length, GrowableArrayLength, 1160357614)         \
   V(_GrowableObjectArray, get:_capacity, GrowableArrayCapacity, 1509781988)    \
   V(_GrowableObjectArray, _setData, GrowableArraySetData, 236295352)           \
   V(_GrowableObjectArray, _setLength, GrowableArraySetLength, 1922121178)      \
   V(_StringBase, get:length, StringBaseLength, 1483460481)                     \
   V(_StringBase, get:isEmpty, StringBaseIsEmpty, 1588094430)                   \
   V(_StringBase, codeUnitAt, StringBaseCodeUnitAt, 1958436584)                 \
-  V(_StringBase, [], StringBaseCharAt, 539412735)                              \
+  V(_StringBase, [], StringBaseCharAt, 1799392702)                             \
   V(_OneByteString, _setAt, OneByteStringSetAt, 1754827784)                    \
   V(_IntegerImplementation, toDouble, IntegerToDouble, 2141284842)             \
   V(_IntegerImplementation, _leftShiftWithMask32, IntegerLeftShiftWithMask32,  \
       2095943661)                                                              \
   V(_Double, toInt, DoubleToInteger, 1328149975)                               \
   V(_Double, truncateToDouble, DoubleTruncate, 615732263)                      \
   V(_Double, roundToDouble, DoubleRound, 622146406)                            \
   V(_Double, floorToDouble, DoubleFloor, 1614014643)                           \
   V(_Double, ceilToDouble, DoubleCeil, 277859570)                              \
   V(_Double, _modulo, DoubleMod, 1443289156)                                   \
@@ skipping 6701 matching lines @@
   ForwardInstructionIterator* current_iterator_;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(FlowGraphVisitor);
 };
 
 
 }  // namespace dart
 
 #endif  // VM_INTERMEDIATE_LANGUAGE_H_