[runtime] Remove the obsolete %_StringCharAt intrinsic.

src/crankshaft/hydrogen.cc

 // Copyright 2013 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.
 
 #include "src/crankshaft/hydrogen.h"
 
 #include <sstream>
 
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast-numbering.h"
@@ skipping 12649 matching lines @@
 // Fast support for string.charAt(n) and string[n].
 void HOptimizedGraphBuilder::GenerateStringCharFromCode(CallRuntime* call) {
   DCHECK(call->arguments()->length() == 1);
   CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
   HValue* char_code = Pop();
   HInstruction* result = NewUncasted<HStringCharFromCode>(char_code);
   return ast_context()->ReturnInstruction(result, call->id());
 }
 
 
-// Fast support for string.charAt(n) and string[n].
-void HOptimizedGraphBuilder::GenerateStringCharAt(CallRuntime* call) {
-  DCHECK(call->arguments()->length() == 2);
-  CHECK_ALIVE(VisitForValue(call->arguments()->at(0)));
-  CHECK_ALIVE(VisitForValue(call->arguments()->at(1)));
-  HValue* index = Pop();
-  HValue* string = Pop();
-  HInstruction* char_code = BuildStringCharCodeAt(string, index);
-  AddInstruction(char_code);
-  HInstruction* result = NewUncasted<HStringCharFromCode>(char_code);
-  return ast_context()->ReturnInstruction(result, call->id());
-}
-
-
 // Fast support for SubString.
 void HOptimizedGraphBuilder::GenerateSubString(CallRuntime* call) {
   DCHECK_EQ(3, call->arguments()->length());
   CHECK_ALIVE(VisitExpressions(call->arguments()));
   PushArgumentsFromEnvironment(call->arguments()->length());
   Callable callable = CodeFactory::SubString(isolate());
   HValue* stub = Add<HConstant>(callable.code());
   HValue* values[] = {context()};
   HInstruction* result =
       New<HCallWithDescriptor>(stub, call->arguments()->length(),
@@ skipping 1003 matching lines @@
     isolate()->GetHTracer()->TraceHydrogen(name(), graph_);
   }
 
 #ifdef DEBUG
   graph_->Verify(false);  // No full verify.
 #endif
 }
 
 }  // namespace internal
 }  // namespace v8