[runtime] Remove the obsolete %_StringCharAt intrinsic.

src/crankshaft/hydrogen.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_CRANKSHAFT_HYDROGEN_H_
 #define V8_CRANKSHAFT_HYDROGEN_H_
 
 #include "src/accessors.h"
 #include "src/allocation.h"
 #include "src/ast/ast-type-bounds.h"
@@ skipping 2246 matching lines @@
 #define FOR_EACH_HYDROGEN_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(ToInteger)                         \
   F(ToName)                            \
   F(ToObject)                          \
   F(ToString)                          \
   F(ToLength)                          \
   F(ToNumber)                          \
   F(IsJSReceiver)                      \
   F(MathPow)                           \
@@ skipping 825 matching lines @@
   }
 
  private:
   HOptimizedGraphBuilder* builder_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_CRANKSHAFT_HYDROGEN_H_