Remove duplicated code from comma-separated Expression parsing

test/mjsunit/es8/syntactic-tail-call-parsing.js

 // 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.
 
 // Flags: --allow-natives-syntax --harmony-explicit-tailcalls
 // Flags: --harmony-do-expressions
 "use strict";
 
 var SyntaxErrorTests = [
   { msg: "Unexpected expression inside tail call",
@@ skipping 115 matching lines @@
       },
       { src: `()=>{ return bar in continue foo() ; }`,
         err: `                    ^^^^^^^^^^^^^^`,
       },
       { src: `()=>{ function* G() { yield continue foo(); } }`,
         err: `                            ^^^^^^^^^^^^^^`,
       },
       { src: `()=>{ (1, 2, 3, continue f() ) => {} }`,
         err: `                ^^^^^^^^^^^^`,
       },
-      { src: `()=>{ (... continue f()) => {}  }`,
-        err: `           ^^^^^^^^^^^^`,
-      },
-      { src: `()=>{ (a, b, c, ... continue f() ) => {}  }`,
-        err: `                    ^^^^^^^^^^^^`,
-      },
       { src: `()=>{ return a <= continue f(); }`,
         err: `                  ^^^^^^^^^^^^`,
       },
       { src: `()=>{ return b > continue f(); }`,
         err: `                 ^^^^^^^^^^^^`,
       },
       { src: `()=>{ return a << continue f(); }`,
         err: `                  ^^^^^^^^^^^^`,
       },
       { src: `()=>{ return b >> continue f(); }`,
@@ skipping 130 matching lines @@
         err: `                           ^^^^^^^^^`,
       },
       { src: `()=> a, continue  eval  ( )  ; `,
         err: `                  ^^^^^^^^^`,
       },
       { src: `()=> a || continue  eval  (' ' )  ; `,
         err: `                    ^^^^^^^^^^^^`,
       },
     ],
   },
+  { msg: "Unexpected token continue",
+    tests: [
+      { src: `()=>{ (... continue f()) => {}  }`,
+        err: `           ^^^^^^^^`,
+      },
+      { src: `()=>{ (a, b, c, ... continue f() ) => {}  }`,

[Dan Ehrenberg, 2016/08/26 22:48:53]

This is also a worse message. It's only acceptable to me because the feature is
unlikely to ever ship.

[nickie, 2016/08/29 08:42:59]

I can live with it; I think it is a bad error message, but the previous one was
even worse.  Unexpected expression inside tail call?  It's the tail call
("continue" expression) that is in the wrong place, not what's inside it.

+        err: `                    ^^^^^^^^`,
+      },
+    ],
+  },
   { msg: "Undefined label 'foo'",
     tests: [
       { src: `()=>{ continue  foo () ; }`,
         err: `                ^^^`,
       },
     ],
   },
 ];
 
 
@@ skipping 77 matching lines @@
 (function() {
   for (var src of NoErrorTests) {
     print("=======================================");
     print("Source   | " + src);
     src = `"use strict"; ` + src;
     Realm.eval(0, src);
     print("PASSED");
     print();
   }
 })();