Improve performance of String.fromCharCodes by implementing it in Dart. Add tow internal natives to…

runtime/vm/intrinsifier.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.
 // Class for intrinsifying functions.
 
 #ifndef VM_INTRINSIFIER_H_
 #define VM_INTRINSIFIER_H_
 
 #include "vm/allocation.h"
 
@@ skipping 65 matching lines @@
   V(_ImmutableArray, [], ImmutableArray_getIndexed, 486821199)                 \
   V(_ImmutableArray, get:length, ImmutableArray_getLength, 433698233)          \
   V(Object, ==, Object_equal, 2126897013)                                      \
   V(_StringBase, get:hashCode, String_getHashCode, 320803993)                  \
   V(_StringBase, get:isEmpty, String_getIsEmpty, 1026765313)                   \
   V(_StringBase, get:length, String_getLength, 320803993)                      \
   V(_StringBase, codeUnitAt, String_codeUnitAt, 984449525)                     \
   V(_OneByteString, get:hashCode, OneByteString_getHashCode, 682660413)        \
   V(_OneByteString, _substringUncheckedNative,                                 \
       OneByteString_substringUnchecked, 713121438)                             \
+  V(_OneByteString, _setAt, OneByteString_setAt, 342452817)                    \
+  V(_OneByteString, _allocate, OneByteString_allocate, 510754908)              \
 
 
 #define MATH_LIB_INTRINSIC_LIST(V)                                             \
   V(::, sqrt, Math_sqrt, 1662640002)                                           \
   V(::, sin, Math_sin, 1273932041)                                             \
   V(::, cos, Math_cos, 1749547468)                                             \
 
 
 #define TYPED_DATA_LIB_INTRINSIC_LIST(V)                                       \
   V(_TypedList, get:length, TypedData_getLength, 1004567191)                   \
@@ skipping 45 matching lines @@
   CORE_LIB_INTRINSIC_LIST(DECLARE_FUNCTION)
   MATH_LIB_INTRINSIC_LIST(DECLARE_FUNCTION)
   TYPED_DATA_LIB_INTRINSIC_LIST(DECLARE_FUNCTION)
 
 #undef DECLARE_FUNCTION
 };
 
 }  // namespace dart
 
 #endif  // VM_INTRINSIFIER_H_