new classes: implement default constructors.

src/parser.h

Index: src/parser.h
diff --git a/src/parser.h b/src/parser.h
index 19036e7739787108d49a4b3a6d215ab5aa17a0aa..57c3acafa7f93c318a1e61cf3903e73bcc3d69b3 100644
--- a/src/parser.h
+++ b/src/parser.h
@@ -840,6 +840,8 @@ class Parser : public ParserBase<ParserTraits> {
   BreakableStatement* LookupBreakTarget(const AstRawString* label, bool* ok);
   IterationStatement* LookupContinueTarget(const AstRawString* label, bool* ok);
 
+  void AssertIsConstruct(ZoneList<Statement*>* body, int pos);
+
   // Factory methods.
   FunctionLiteral* DefaultConstructor(bool call_super, Scope* scope, int pos,
                                       int end_pos);