add $ to variable name character matching patterns in repl completer

lib/repl.js

@@ -266,8 +266,8 @@ REPLServer.prototype.complete = function (line) {
   //   spam.eggs.<|>  # completions for 'spam.eggs' with filter ''
   //   foo<|>         # all scope vars with filter 'foo'
   //   foo.<|>        # completions for 'foo' with filter ''
-  else if (line.length === 0 || line[line.length-1].match(/\w|\./)) {
+  else if (line.length === 0 || line[line.length-1].match(/\w|\.|\$/)) {
-    var simpleExpressionPat = /(([a-zA-Z_]\w*)\.)*([a-zA-Z_]\w*)\.?$/;
+    var simpleExpressionPat = /(([a-zA-Z_$](?:\w|\$)*)\.)*([a-zA-Z_$](?:\w|\$)*)\.?$/;
     match = simpleExpressionPat.exec(line);
     if (line.length === 0 || match) {
       var expr;