[string] Add a fast path to String.p.replace

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index cc8056402d88dc3859facd8fe85e530a686a196c..5fd0893216759a666231427ce0965566831666e2 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -11440,8 +11440,10 @@ int String::IndexOf(Isolate* isolate, Handle<String> receiver,
 }
 
 MaybeHandle<String> String::GetSubstitution(Isolate* isolate, Match* match,
-                                            Handle<String> replacement) {
+                                            Handle<String> replacement,
+                                            int start_index) {
   DCHECK_IMPLIES(match->HasNamedCaptures(), FLAG_harmony_regexp_named_captures);
+  DCHECK_GE(start_index, 0);
 
   Factory* factory = isolate->factory();
 
@@ -11452,7 +11454,8 @@ MaybeHandle<String> String::GetSubstitution(Isolate* isolate, Match* match,
 
   Handle<String> dollar_string =
       factory->LookupSingleCharacterStringFromCode('$');
-  int next_dollar_ix = String::IndexOf(isolate, replacement, dollar_string, 0);
+  int next_dollar_ix =
+      String::IndexOf(isolate, replacement, dollar_string, start_index);
   if (next_dollar_ix < 0) {
     return replacement;
   }