[runtime] Remove the obsolete %_StringCharAt intrinsic.

src/runtime/runtime.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_RUNTIME_RUNTIME_H_
 #define V8_RUNTIME_RUNTIME_H_
 
 #include "src/allocation.h"
 #include "src/base/platform/time.h"
 #include "src/objects.h"
@@ skipping 825 matching lines @@
   F(TruncateString, 2, 1)                 \
   F(NewString, 2, 1)                      \
   F(StringLessThan, 2, 1)                 \
   F(StringLessThanOrEqual, 2, 1)          \
   F(StringGreaterThan, 2, 1)              \
   F(StringGreaterThanOrEqual, 2, 1)       \
   F(StringEqual, 2, 1)                    \
   F(StringNotEqual, 2, 1)                 \
   F(FlattenString, 1, 1)                  \
   F(StringCharFromCode, 1, 1)             \
-  F(StringCharAt, 2, 1)                   \
   F(ExternalStringGetChar, 2, 1)          \
   F(OneByteSeqStringGetChar, 2, 1)        \
   F(OneByteSeqStringSetChar, 3, 1)        \
   F(TwoByteSeqStringGetChar, 2, 1)        \
   F(TwoByteSeqStringSetChar, 3, 1)        \
   F(StringCharCodeAt, 2, 1)
 
 #define FOR_EACH_INTRINSIC_SYMBOL(F) \
   F(CreateSymbol, 1, 1)              \
   F(CreatePrivateSymbol, 1, 1)       \
@@ skipping 304 matching lines @@
 
 class DeclareGlobalsEvalFlag : public BitField<bool, 0, 1> {};
 class DeclareGlobalsNativeFlag : public BitField<bool, 1, 1> {};
 STATIC_ASSERT(LANGUAGE_END == 3);
 class DeclareGlobalsLanguageMode : public BitField<LanguageMode, 2, 2> {};
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_RUNTIME_RUNTIME_H_