[regexp] Add stub for RegExpExec instead of inlining

src/code-factory.h

Index: src/code-factory.h
diff --git a/src/code-factory.h b/src/code-factory.h
index 0ee92f7c25eece0684dd8fdfe090be84d3446f2a..93611fb4886d31c54bee5b71b751284a21cc016e 100644
--- a/src/code-factory.h
+++ b/src/code-factory.h
@@ -96,8 +96,13 @@ class V8_EXPORT_PRIVATE CodeFactory final {
                                       OrdinaryToPrimitiveHint hint);
   static Callable NumberToString(Isolate* isolate);
 
+  // Platform-dependent entry point into the generated irregexp matcher code.
   static Callable RegExpExec(Isolate* isolate);
 
+  // Implements part of the specced glue logic around RegExp.prototype.exec.
+  // Usually results in a call to CodeFactory::RegExpExec.
+  static Callable RegExpExecInternal(Isolate* isolate, bool is_fastpath);
+
   static Callable Add(Isolate* isolate);
   static Callable Subtract(Isolate* isolate);
   static Callable Multiply(Isolate* isolate);