Remove ExpressionParser in favor of ParseContext#safe_parse

lib/liquid/parser.rb

@@ -2,8 +2,6 @@
 
 module Liquid
   class Parser
-    attr_reader :tokens
-
     def initialize(input)
       ss = input.is_a?(StringScanner) ? input : StringScanner.new(input)
       @tokens = Lexer.tokenize(ss)
@@ -84,10 +82,6 @@ module Liquid
       str
     end
 
-    def point
-      @p
-    end
-
     def variable_lookups
       str = +""
       loop do