Add location information to group AST node

lib/parser.js

@@ -236,7 +236,7 @@ function peg$parse(input, options) {
         // nodes that already isolate label scope themselves. This leaves us with
         // "labeled" and "sequence".
         return expression.type === "labeled" || expression.type === "sequence"
-            ? { type: "group", expression: expression }
+            ? { type: "group", expression: expression, location: location() }
             : expression;
       };
   var peg$c32 = function(name) {

src/parser.pegjs

@@ -180,7 +180,7 @@ PrimaryExpression
       // nodes that already isolate label scope themselves. This leaves us with
       // "labeled" and "sequence".
       return expression.type === "labeled" || expression.type === "sequence"
-          ? { type: "group", expression: expression }
+          ? { type: "group", expression: expression, location: location() }
           : expression;
     }