Implement parsing of ES6 Rest Parameters

src/scanner.cc

Index: src/scanner.cc
diff --git a/src/scanner.cc b/src/scanner.cc
index d499e9b996dbbf0e8c348e49b0ecb678431fbb13..ea8586ed263b7b8da4fffc6a7287c8282859be61 100644
--- a/src/scanner.cc
+++ b/src/scanner.cc
@@ -599,6 +599,15 @@ void Scanner::Scan() {
           token = ScanNumber(true);
         } else {
           token = Token::PERIOD;
+          if (c0_ == '.') {

[arv (Not doing code reviews), 2015/01/30 05:28:13]

With this we change the error message in the following case:

  a...b

from

  SyntaxError: Unexpected token .

to

  SyntaxError: Unexpected token ...

I'm not sure that is a big deal though.

[marja, 2015/01/30 08:33:31]

Maybe that's a reason to at least check the harmony flag here so that that error
would only occur when the flag is on? (But I don't think it's a hugely important
thing either.)

+            Advance();
+            if (c0_ == '.') {
+              Advance();
+              token = Token::ELLIPSIS;
+            } else {
+              PushBack('.');
+            }
+          }
         }
         break;