Revert "Use strip & empty? to detect Whitespaces"

This reverts commit dd7ed00ec4.

lib/liquid/block_body.rb

@@ -7,6 +7,7 @@ module Liquid
     LiquidTagToken      = /\A\s*(\w+)\s*(.*?)\z/o
     FullToken           = /\A#{TagStart}#{WhitespaceControl}?(\s*)(\w+)(\s*)(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
     ContentOfVariable   = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
+    WhitespaceOrNothing = /\A\s*\z/
     TAGSTART            = "{%"
     VARSTART            = "{{"
 
@@ -36,7 +37,7 @@ module Liquid
 
     private def parse_for_liquid_tag(tokenizer, parse_context)
       while (token = tokenizer.shift)
-        unless token.strip.empty?
+        unless token.empty? || token =~ WhitespaceOrNothing
           unless token =~ LiquidTagToken
             # line isn't empty but didn't match tag syntax, yield and let the
             # caller raise a syntax error
@@ -149,7 +150,7 @@ module Liquid
           end
           parse_context.trim_whitespace = false
           @nodelist << token
-          @blank &&= token.strip.empty?
+          @blank &&= !!(token =~ WhitespaceOrNothing)
         end
         parse_context.line_number = tokenizer.line_number
       end