Allow expand in array literals

lib/ast.js

@@ -371,15 +371,15 @@ var AST_Toplevel = DEFNODE("Toplevel", "globals", {
     }
 }, AST_Scope);
 
-var AST_Expansion = DEFNODE("Expansion", "symbol", {
+var AST_Expansion = DEFNODE("Expansion", "expression", {
     $documentation: "An expandible argument, such as ...rest, a splat, such as [1,2,...all], or an expansion in a variable declaration, such as var [first, ...rest] = list",
     $propdoc: {
-        symbol: "AST_Symbol the thing to be expanded"
+        expression: "AST_Symbol the thing to be expanded"
     },
     _walk: function(visitor) {
         var self = this;
         return visitor._visit(this, function(){
-            self.symbol.walk(visitor);
+            self.expression.walk(visitor);
         });
     }
 });
@@ -516,7 +516,7 @@ var AST_Destructuring = DEFNODE("Destructuring", "names is_array default", {
                 out.push(node);
             }
             if (node instanceof AST_Expansion) {
-                out.push(node.symbol);
+                out.push(node.expression);
             }
         }));
         return out;