[builtins] Move StringIndexOf to a builtin.

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index eb0cb4a52ebdefbf3d1b83c8f0027933efb6b3f0..319fc7ba7375e23d31ce697405b92bdf7c73bed9 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -11599,20 +11599,38 @@ ComparisonResult String::Compare(Handle<String> x, Handle<String> y) {
   return result;
 }
 
-int String::IndexOf(Isolate* isolate, Handle<String> sub, Handle<String> pat,
-                    int start_index) {
-  DCHECK(0 <= start_index);
-  DCHECK(start_index <= sub->length());
+Object* String::IndexOf(Isolate* isolate, Handle<Object> receiver,
+                        Handle<Object> pattern, Handle<Object> position) {
+  if (receiver->IsNull(isolate) || receiver->IsUndefined(isolate)) {
+    THROW_NEW_ERROR_RETURN_FAILURE(
+        isolate, NewTypeError(MessageTemplate::kCalledOnNullOrUndefined,
+                              isolate->factory()->NewStringFromAsciiChecked(
+                                  "String.prototype.lastIndexOf")));
+  }
+  Handle<String> sub;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, sub,
+                                     Object::ToString(isolate, receiver));
+  Handle<String> pat;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, pat,
+                                     Object::ToString(isolate, pattern));
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(isolate, position,
+                                     Object::ToInteger(isolate, position));
 
-  int pattern_length = pat->length();
-  if (pattern_length == 0) return start_index;
+  double position_number = std::max(position->Number(), 0.0);
+  position_number =
+      std::min(position_number, static_cast<double>(sub->length()));
+  uint32_t start_index = static_cast<uint32_t>(position_number);
 
-  int subject_length = sub->length();
-  if (start_index + pattern_length > subject_length) return -1;
+  uint32_t pattern_length = pat->length();
+  if (pattern_length == 0) return Smi::FromInt(start_index);
+
+  uint32_t subject_length = sub->length();
+  if (start_index + pattern_length > subject_length) return Smi::FromInt(-1);
 
   sub = String::Flatten(sub);
   pat = String::Flatten(pat);
 
+  int first_index = -1;
   DisallowHeapAllocation no_gc;  // ensure vectors stay valid
   // Extract flattened substrings of cons strings before getting encoding.
   String::FlatContent seq_sub = sub->GetFlatContent();
@@ -11622,18 +11640,23 @@ int String::IndexOf(Isolate* isolate, Handle<String> sub, Handle<String> pat,
   if (seq_pat.IsOneByte()) {
     Vector<const uint8_t> pat_vector = seq_pat.ToOneByteVector();
     if (seq_sub.IsOneByte()) {
-      return SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
-                          start_index);
+      first_index = SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
+                                 start_index);
+    } else {
+      first_index = SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector,
+                                 start_index);
+    }
+  } else {
+    Vector<const uc16> pat_vector = seq_pat.ToUC16Vector();
+    if (seq_sub.IsOneByte()) {
+      first_index = SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
+                                 start_index);
+    } else {
+      first_index = SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector,
+                                 start_index);
     }
-    return SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector,
-                        start_index);
-  }
-  Vector<const uc16> pat_vector = seq_pat.ToUC16Vector();
-  if (seq_sub.IsOneByte()) {
-    return SearchString(isolate, seq_sub.ToOneByteVector(), pat_vector,
-                        start_index);
   }
-  return SearchString(isolate, seq_sub.ToUC16Vector(), pat_vector, start_index);
+  return Smi::FromInt(first_index);
 }
 
 namespace {  // for String.Prototype.lastIndexOf