[regexp] Implement regexp groups as wrapper.

src/regexp/regexp-ast.cc

Index: src/regexp/regexp-ast.cc
diff --git a/src/regexp/regexp-ast.cc b/src/regexp/regexp-ast.cc
index b5c2bb6d91d9f3b060366171a21bf645ff8a805a..ba1818a6febb0b6c66b87a7c7e56cf9c8ba51fa9 100644
--- a/src/regexp/regexp-ast.cc
+++ b/src/regexp/regexp-ast.cc
@@ -264,6 +264,12 @@ void* RegExpUnparser::VisitCapture(RegExpCapture* that, void* data) {
   return NULL;
 }
 
+void* RegExpUnparser::VisitGroup(RegExpGroup* that, void* data) {
+  os_ << "( ";

[erikcorry, 2017/01/16 11:34:32]

Should probably be "(?:"

[jgruber, 2017/01/16 11:35:40]

Nit: Seems like the convention is to use a char after the opening paren for
disambiguation.

+  that->body()->Accept(this, data);
+  os_ << ")";
+  return NULL;
+}
 
 void* RegExpUnparser::VisitLookaround(RegExpLookaround* that, void* data) {
   os_ << "(";