Remove duplicated code from comma-separated Expression parsing

test/mjsunit/es8/syntactic-tail-call-parsing-sloppy.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
 
 var SyntaxErrorTests = [
   { msg: "Unexpected expression inside tail call",
     tests: [
@@ skipping 124 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 165 matching lines @@
         err: `          ^^^^^^^^^^^^^^^^`,
       },
       { src: `()=> a && continue  foo () ;`,
         err: `          ^^^^^^^^^^^^^^^^`,
       },
       { src: `()=> a ? continue  foo () : b;`,
         err: `         ^^^^^^^^^^^^^^^^`,
       },
     ],
   },
+  { msg: "Unexpected token continue",
+    tests: [
+      { src: `()=>{ (... continue f()) => {}  }`,
+        err: `           ^^^^^^^^`,
+      },
+      { src: `()=>{ (a, b, c, ... continue f() ) => {}  }`,
+        err: `                    ^^^^^^^^`,
+      },
+    ],
+  },
   { msg: "Undefined label 'foo'",
     tests: [
       { src: `()=>{ continue  foo () ; }`,
         err: `                ^^^`,
       },
     ],
   },
 ];
 
 
@@ skipping 55 matching lines @@
 
 (function() {
   for (var src of NoErrorTests) {
     print("=======================================");
     print("Source   | " + src);
     Realm.eval(0, src);
     print("PASSED");
     print();
   }
 })();