Make StringCharCodeAt runtime function do what it name implies and not

src/runtime.cc

Index: src/runtime.cc
diff --git a/src/runtime.cc b/src/runtime.cc
index d53b13d07fca9363e9913429ded8cb084576a4c4..80e67cc87585ce206e5ff200e0ea3a53c1240534 100644
--- a/src/runtime.cc
+++ b/src/runtime.cc
@@ -1638,22 +1638,6 @@ static Object* Runtime_SetCode(Arguments args) {
 }
 
 
-static Object* CharCodeAt(String* subject, Object* index) {
-  uint32_t i = 0;
-  if (!index->ToArrayIndex(&i)) return Heap::nan_value();
-  // Flatten the string.  If someone wants to get a char at an index
-  // in a cons string, it is likely that more indices will be
-  // accessed.
-  Object* flat = subject->TryFlatten();
-  if (flat->IsFailure()) return flat;
-  subject = String::cast(flat);
-  if (i >= static_cast<uint32_t>(subject->length())) {
-    return Heap::nan_value();
-  }
-  return Smi::FromInt(subject->Get(i));
-}
-
-
 static Object* CharFromCode(Object* char_code) {
   uint32_t code;
   if (char_code->ToArrayIndex(&code)) {
@@ -1671,21 +1655,31 @@ static Object* Runtime_StringCharCodeAt(Arguments args) {
 
   CONVERT_CHECKED(String, subject, args[0]);
   Object* index = args[1];
-  return CharCodeAt(subject, index);
-}
+  RUNTIME_ASSERT(index->IsNumber());
 
+  uint32_t i = 0;
+  if (index->IsSmi()) {
+    int value = Smi::cast(index)->value();
+    if (value < 0) return Heap::nan_value();
+    i = value;
+  } else {
+    ASSERT(index->IsHeapNumber());
+    double value = HeapNumber::cast(index)->value();
+    i = static_cast<uint32_t>(value);
+  }
 
-static Object* Runtime_StringCharAt(Arguments args) {
-  NoHandleAllocation ha;
-  ASSERT(args.length() == 2);
+  // Flatten the string.  If someone wants to get a char at an index
+  // in a cons string, it is likely that more indices will be
+  // accessed.
+  Object* flat = subject->TryFlatten();
+  if (flat->IsFailure()) return flat;
+  subject = String::cast(flat);
 
-  CONVERT_CHECKED(String, subject, args[0]);
-  Object* index = args[1];
-  Object* code = CharCodeAt(subject, index);
-  if (code == Heap::nan_value()) {
-    return Heap::undefined_value();
+  if (i >= static_cast<uint32_t>(subject->length())) {
+    return Heap::nan_value();
   }
-  return CharFromCode(code);
+
+  return Smi::FromInt(subject->Get(i));
 }
 
 
@@ -5344,6 +5338,9 @@ static Object* Runtime_NumberToInteger(Arguments args) {
 }
 
 
+
+
+
 static Object* Runtime_NumberToIntegerMapMinusZero(Arguments args) {
   NoHandleAllocation ha;
   ASSERT(args.length() == 1);