Revert "Instrument usage of bug with iteration of String with offset or 0 limit (#1667)"

This reverts commit c743936a78.

lib/liquid/utils.rb

@@ -16,11 +16,7 @@ module Liquid
 
       # Maintains Ruby 1.8.7 String#each behaviour on 1.9
       if collection.is_a?(String)
-        return [] if collection.empty?
-        if from > 0 || to == 0
-          Usage.increment("string_slice_bug")
-        end
-        return [collection]
+        return collection.empty? ? [] : [collection]
       end
       return [] unless collection.respond_to?(:each)