Revert of [builtins] Migrate String.prototype.charCodeAt and String.prototype.charAt to TurboFan.

src/builtins.h

Index: src/builtins.h
diff --git a/src/builtins.h b/src/builtins.h
index ea47f7e6f2a8e435d60da628235e5172add7fd90..294929a290189691014ea048fb1af2a669e22ea5 100644
--- a/src/builtins.h
+++ b/src/builtins.h
@@ -310,9 +310,7 @@
   V(MathRound, 2)                \
   V(MathSqrt, 2)                 \
   V(MathTrunc, 2)                \
-  V(ObjectHasOwnProperty, 2)     \
-  V(StringPrototypeCharAt, 2)    \
-  V(StringPrototypeCharCodeAt, 2)
+  V(ObjectHasOwnProperty, 2)
 
 // Define list of builtin handlers implemented in assembly.
 #define BUILTIN_LIST_H(V)                    \
@@ -628,13 +626,6 @@
   static void Generate_ObjectHasOwnProperty(
       compiler::CodeStubAssembler* assembler);
 
-  // ES6 section 21.1.3.1 String.prototype.charAt ( pos )
-  static void Generate_StringPrototypeCharAt(
-      compiler::CodeStubAssembler* assembler);
-  // ES6 section 21.1.3.2 String.prototype.charCodeAt ( pos )
-  static void Generate_StringPrototypeCharCodeAt(
-      compiler::CodeStubAssembler* assembler);
-
   static void Generate_StringConstructor(MacroAssembler* masm);
   static void Generate_StringConstructor_ConstructStub(MacroAssembler* masm);
   static void Generate_OnStackReplacement(MacroAssembler* masm);