VM: Optimized code for all of [External]{One|Two}ByteString::codeUnitAt.

runtime/vm/flow_graph_type_propagator.cc

 // 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.
 
 #include "vm/flow_graph_type_propagator.h"
 
 #include "vm/cha.h"
 #include "vm/bit_vector.h"
 #include "vm/il_printer.h"
 #include "vm/regexp_assembler.h"
@@ skipping 903 matching lines @@
   return *value()->Type();
 }
 
 
 CompileType StoreLocalInstr::ComputeType() const {
   // Returns stored value.
   return *value()->Type();
 }
 
 
-CompileType StringFromCharCodeInstr::ComputeType() const {
-  return CompileType::FromCid(cid_);
+CompileType OneByteStringFromCharCodeInstr::ComputeType() const {
+  return CompileType::FromCid(kOneByteStringCid);
 }
 
 
 CompileType StringToCharCodeInstr::ComputeType() const {
     return CompileType::FromCid(kSmiCid);
 }
 
 
 CompileType StringInterpolateInstr::ComputeType() const {
   // TODO(srdjan): Do better and determine if it is a one or two byte string.
@@ skipping 450 matching lines @@
 CompileType MergedMathInstr::ComputeType() const {
   return CompileType::Dynamic();
 }
 
 
 CompileType ExtractNthOutputInstr::ComputeType() const {
   return CompileType::FromCid(definition_cid_);
 }
 
 }  // namespace dart