Remove unused StringCharCodeAt stub.

src/x64/lithium-codegen-x64.cc

 // Copyright 2011 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 696 matching lines @@
     case CodeStub::RegExpExec: {
       RegExpExecStub stub;
       CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
       break;
     }
     case CodeStub::SubString: {
       SubStringStub stub;
       CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
       break;
     }
-    case CodeStub::StringCharAt: {
-      StringCharAtStub stub;
-      CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
-      break;
-    }
     case CodeStub::NumberToString: {
       NumberToStringStub stub;
       CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
       break;
     }
     case CodeStub::StringAdd: {
       StringAddStub stub(NO_STRING_ADD_FLAGS);
       CallCode(stub.GetCode(), RelocInfo::CODE_TARGET, instr);
       break;
     }
@@ skipping 3036 matching lines @@
   RegisterEnvironmentForDeoptimization(environment);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64