[runtime] Remove the obsolete %_StringCharAt intrinsic.

src/full-codegen/full-codegen.h

 // Copyright 2012 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_FULL_CODEGEN_FULL_CODEGEN_H_
 #define V8_FULL_CODEGEN_FULL_CODEGEN_H_
 
 #include "src/allocation.h"
 #include "src/assert-scope.h"
 #include "src/ast/ast.h"
@@ skipping 494 matching lines @@
 #define FOR_EACH_FULL_CODE_INTRINSIC(F) \
   F(IsSmi)                              \
   F(IsArray)                            \
   F(IsTypedArray)                       \
   F(IsRegExp)                           \
   F(IsJSProxy)                          \
   F(Call)                               \
   F(NewObject)                          \
   F(ValueOf)                            \
   F(StringCharFromCode)                 \
-  F(StringCharAt)                       \
   F(OneByteSeqStringSetChar)            \
   F(TwoByteSeqStringSetChar)            \
   F(IsJSReceiver)                       \
   F(MathPow)                            \
   F(HasCachedArrayIndex)                \
   F(GetCachedArrayIndex)                \
   F(GetSuperConstructor)                \
   F(DebugBreakInOptimizedCode)          \
   F(ClassOf)                            \
   F(StringCharCodeAt)                   \
@@ skipping 532 matching lines @@
   Address start_;
   Address instruction_start_;
   uint32_t length_;
 };
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_FULL_CODEGEN_FULL_CODEGEN_H_