Revert "Re-add the #random_string(len) method to pass specs."

This reverts commit bd8918e.

Author: joevennix

lib/rex/exploitation/jsobfu.rb

@@ -83,7 +83,7 @@ def initialize(parent=nil)
     def random_var_name
       len = 1
       loop do
-        text = random_string(len)
+        text = @rand_gen.generate(len)
         unless has_key?(text) or
           RESERVED_KEYWORDS.include?(text) or
           BUILTIN_VARS.include?(text)
@@ -100,11 +100,6 @@ def has_key?(key)
       super or (@parent and @parent.has_key?(key))
     end
 
-    # @return [String] a random string that can be used as a var
-    def random_string(len)
-      @rand_gen.generate(len)
-    end
-
   end
 
   #