Remove Execution::CharAt

BUG=

Review URL: https://codereview.chromium.org/1143153004

Cr-Commit-Position: refs/heads/master@{#28758}

src/execution.cc

@@ -602,35 +602,6 @@ MaybeHandle<JSRegExp> Execution::NewJSRegExp(Handle<String> pattern,
 }
 
 
-Handle<Object> Execution::CharAt(Handle<String> string, uint32_t index) {
-  Isolate* isolate = string->GetIsolate();
-  Factory* factory = isolate->factory();
-
-  int int_index = static_cast<int>(index);
-  if (int_index < 0 || int_index >= string->length()) {
-    return factory->undefined_value();
-  }
-
-  Handle<Object> char_at = Object::GetProperty(
-      isolate->js_builtins_object(),
-      factory->char_at_string()).ToHandleChecked();
-  if (!char_at->IsJSFunction()) {
-    return factory->undefined_value();
-  }
-
-  Handle<Object> index_object = factory->NewNumberFromInt(int_index);
-  Handle<Object> index_arg[] = { index_object };
-  Handle<Object> result;
-  if (!TryCall(Handle<JSFunction>::cast(char_at),
-               string,
-               arraysize(index_arg),
-               index_arg).ToHandle(&result)) {
-    return factory->undefined_value();
-  }
-  return result;
-}
-
-
 Handle<String> Execution::GetStackTraceLine(Handle<Object> recv,
                                             Handle<JSFunction> fun,
                                             Handle<Object> pos,

src/execution.h

@@ -94,9 +94,6 @@ class Execution final : public AllStatic {
   MUST_USE_RESULT static MaybeHandle<JSRegExp> NewJSRegExp(
       Handle<String> pattern, Handle<String> flags);
 
-  // Used to implement [] notation on strings (calls JS code)
-  static Handle<Object> CharAt(Handle<String> str, uint32_t index);
-
   static Handle<Object> GetFunctionFor();
   static Handle<String> GetStackTraceLine(Handle<Object> recv,
                                           Handle<JSFunction> fun,

src/runtime/runtime-object.cc

@@ -17,12 +17,10 @@ namespace internal {
 // Returns a single character string where first character equals
 // string->Get(index).
 static Handle<Object> GetCharAt(Handle<String> string, uint32_t index) {
-  if (index < static_cast<uint32_t>(string->length())) {
-    Factory* factory = string->GetIsolate()->factory();
-    return factory->LookupSingleCharacterStringFromCode(
-        String::Flatten(string)->Get(index));
-  }
-  return Execution::CharAt(string, index);
+  DCHECK_LT(index, static_cast<uint32_t>(string->length()));
+  Factory* factory = string->GetIsolate()->factory();
+  return factory->LookupSingleCharacterStringFromCode(
+      String::Flatten(string)->Get(index));
 }
 
 
@@ -30,7 +28,8 @@ MaybeHandle<Object> Runtime::GetElementOrCharAt(Isolate* isolate,
                                                 Handle<Object> object,
                                                 uint32_t index) {
   // Handle [] indexing on Strings
-  if (object->IsString()) {
+  if (object->IsString() &&
+      index < static_cast<uint32_t>(String::cast(*object)->length())) {
     Handle<Object> result = GetCharAt(Handle<String>::cast(object), index);
     if (!result->IsUndefined()) return result;
   }