[regexp] Migrate constructor and compile to CSA

src/regexp/regexp-utils.cc

 // Copyright 2016 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/regexp/regexp-utils.h"
 
 #include "src/factory.h"
 #include "src/isolate.h"
 #include "src/objects-inl.h"
 #include "src/regexp/jsregexp.h"
@@ skipping 100 matching lines @@
 
     return Execution::Call(isolate, regexp_exec, regexp, argc, argv.start());
   }
 }
 
 Maybe<bool> RegExpUtils::IsRegExp(Isolate* isolate, Handle<Object> object) {
   if (!object->IsJSReceiver()) return Just(false);
 
   Handle<JSReceiver> receiver = Handle<JSReceiver>::cast(object);
 
-  if (isolate->regexp_function()->initial_map() == receiver->map()) {
-    // Fast-path for unmodified JSRegExp instances.
-    // TODO(ishell): Adapt for new fast-path logic.
-    return Just(true);
-  }
-
   Handle<Object> match;
   ASSIGN_RETURN_ON_EXCEPTION_VALUE(
       isolate, match,
       JSObject::GetProperty(receiver, isolate->factory()->match_symbol()),
       Nothing<bool>());
 
   if (!match->IsUndefined(isolate)) return Just(match->BooleanValue());
   return Just(object->IsJSRegExp());
 }
 
@@ skipping 46 matching lines @@
 
   const int last_index = Handle<Smi>::cast(last_index_obj)->value();
   const int new_last_index =
       AdvanceStringIndex(isolate, string, last_index, unicode);
 
   return SetLastIndex(isolate, regexp, new_last_index);
 }
 
 }  // namespace internal
 }  // namespace v8