[regexp] Implement regexp groups as wrapper.

src/regexp/regexp-parser.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-parser.h"
 
 #include "src/char-predicates-inl.h"
 #include "src/factory.h"
 #include "src/isolate.h"
 #include "src/objects-inl.h"
@@ skipping 198 matching lines @@
 
         // Build result of subexpression.
         if (group_type == CAPTURE) {
           if (state->IsNamedCapture()) {
             CreateNamedCaptureAtIndex(state->capture_name(),
                                       capture_index CHECK_FAILED);
           }
           RegExpCapture* capture = GetCapture(capture_index);
           capture->set_body(body);
           body = capture;
-        } else if (group_type != GROUPING) {
+        } else if (group_type == GROUPING) {
+          body = new (zone()) RegExpGroup(body);
+        } else {
           DCHECK(group_type == POSITIVE_LOOKAROUND ||
                  group_type == NEGATIVE_LOOKAROUND);
           bool is_positive = (group_type == POSITIVE_LOOKAROUND);
           body = new (zone()) RegExpLookaround(
               body, is_positive, end_capture_index - capture_index,
               capture_index, state->lookaround_type());
         }
 
         // Restore previous state.
         state = state->previous_state();
@@ skipping 1561 matching lines @@
     return false;
   }
   terms_.Add(new (zone()) RegExpQuantifier(min, max, quantifier_type, atom),
              zone());
   LAST(ADD_TERM);
   return true;
 }
 
 }  // namespace internal
 }  // namespace v8