Remove js.Sequence and use binary comma operator instead.

sdk/lib/_internal/compiler/implementation/js/printer.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 part of js;
 
 class Printer implements NodeVisitor {
   final bool shouldCompressOutput;
   leg.Compiler compiler;
   leg.CodeBuffer outBuffer;
@@ skipping 463 matching lines @@
       visit(node);
     }
   }
 
   visitVariableDeclarationList(VariableDeclarationList list) {
     out("var ");
     visitCommaSeparated(list.declarations, ASSIGNMENT,
                         newInForInit: inForInit, newAtStatementBegin: false);
   }
 
-  visitSequence(Sequence sequence) {
-    // Note that we only require that the entries are expressions and not
-    // assignments. This means that nested sequences are not put into
-    // parenthesis.
-    visitCommaSeparated(sequence.expressions, EXPRESSION,
-                        newInForInit: false,
-                        newAtStatementBegin: atStatementBegin);
-  }
-
   visitAssignment(Assignment assignment) {
     visitNestedExpression(assignment.leftHandSide, LEFT_HAND_SIDE,
                           newInForInit: inForInit,
                           newAtStatementBegin: atStatementBegin);
     if (assignment.value != null) {
       spaceOut();
       String op = assignment.op;
       if (op != null) out(op);
       out("=");
       spaceOut();
@@ skipping 46 matching lines @@
 
   visitBinary(Binary binary) {
     Expression left = binary.left;
     Expression right = binary.right;
     String op = binary.op;
     int leftPrecedenceRequirement;
     int rightPrecedenceRequirement;
     bool leftSpace = true;   // left<HERE>op right
     switch (op) {
       case ',':
+        //  x, (y, z) <=> (x, y), z.
         leftPrecedenceRequirement = EXPRESSION;
-        rightPrecedenceRequirement = LOGICAL_OR;
+        rightPrecedenceRequirement = EXPRESSION;
         leftSpace = false;
         break;
       case "||":
         leftPrecedenceRequirement = LOGICAL_OR;
         // x || (y || z) <=> (x || y) || z.
         rightPrecedenceRequirement = LOGICAL_OR;
         break;
       case "&&":
         leftPrecedenceRequirement = LOGICAL_AND;
         // x && (y && z) <=> (x && y) && z.
@@ skipping 597 matching lines @@
         codes.add(nthLetter((n ~/ nameSpaceSize) % LETTERS));
       }
       codes.add(charCodes.$0 + digit);
       newName = new String.fromCharCodes(codes);
     }
     assert(new RegExp(r'[a-zA-Z][a-zA-Z0-9]*').hasMatch(newName));
     maps.last[oldName] = newName;
     return newName;
   }
 }