ruby-mode: Recognize instance or global var as first arg in parenless call

* lisp/progmodes/ruby-mode.el (ruby-smie--args-separator-p):
Recognize instance or global var as first arg in parenless call.

* test/lisp/progmodes/ruby-mode-resources/ruby.rb: Add example.

lisp/progmodes/ruby-mode.el

@@ -468,7 +468,7 @@ This only affects the output of the command `ruby-toggle-block'."
                                              "else" "elsif" "do" "end" "and")
                                            'symbols))))
          (memq (car (syntax-after pos)) '(7 15))
-         (looking-at "[([]\\|[-+!~:]\\(?:\\sw\\|\\s_\\)")))))
+         (looking-at "[([]\\|[-+!~:@$]\\(?:\\sw\\|\\s_\\)")))))
 
 (defun ruby-smie--before-method-name ()
   ;; Only need to be accurate when method has keyword name.

test/lisp/progmodes/ruby-mode-resources/ruby.rb

@@ -174,6 +174,9 @@ qux :+,
     bar,
     :a
 
+zzz @abc,
+    4
+
 b = $:
 c = ??