[turbofan] Lower StringCharCodeAt to a dedicated builtin.

src/builtins/builtins.h

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef V8_BUILTINS_BUILTINS_H_
 #define V8_BUILTINS_BUILTINS_H_
 
 #include "src/base/flags.h"
 #include "src/handles.h"
 
@@ skipping 87 matching lines @@
   ASM(StackCheck)                                                              \
                                                                                \
   /* String helpers */                                                         \
   TFS(StringEqual, BUILTIN, kNoExtraICState, Compare)                          \
   TFS(StringNotEqual, BUILTIN, kNoExtraICState, Compare)                       \
   TFS(StringLessThan, BUILTIN, kNoExtraICState, Compare)                       \
   TFS(StringLessThanOrEqual, BUILTIN, kNoExtraICState, Compare)                \
   TFS(StringGreaterThan, BUILTIN, kNoExtraICState, Compare)                    \
   TFS(StringGreaterThanOrEqual, BUILTIN, kNoExtraICState, Compare)             \
   TFS(StringCharAt, BUILTIN, kNoExtraICState, StringCharAt)                    \
+  TFS(StringCharCodeAt, BUILTIN, kNoExtraICState, StringCharCodeAt)            \
                                                                                \
   /* Interpreter */                                                            \
   ASM(InterpreterEntryTrampoline)                                              \
   ASM(InterpreterPushArgsAndCall)                                              \
   ASM(InterpreterPushArgsAndCallFunction)                                      \
   ASM(InterpreterPushArgsAndTailCall)                                          \
   ASM(InterpreterPushArgsAndTailCallFunction)                                  \
   ASM(InterpreterPushArgsAndConstruct)                                         \
   ASM(InterpreterPushArgsAndConstructFunction)                                 \
   ASM(InterpreterPushArgsAndConstructArray)                                    \
@@ skipping 735 matching lines @@
 
   friend class Isolate;
 
   DISALLOW_COPY_AND_ASSIGN(Builtins);
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_BUILTINS_BUILTINS_H_