Remove unused Arel::Compatibility::Wheres

This class is no longer used since 9cbfc8a370.

activerecord/lib/arel.rb

@@ -13,7 +13,6 @@ require "arel/alias_predication"
 require "arel/order_predications"
 require "arel/table"
 require "arel/attributes"
-require "arel/compatibility/wheres"
 
 require "arel/visitors"
 require "arel/collectors/sql_string"

activerecord/lib/arel/compatibility/wheres.rb

@@ -1,35 +0,0 @@
-# frozen_string_literal: true
-
-module Arel # :nodoc: all
-  module Compatibility # :nodoc:
-    class Wheres # :nodoc:
-      include Enumerable
-
-      module Value # :nodoc:
-        attr_accessor :visitor
-        def value
-          visitor.accept self
-        end
-
-        def name
-          super.to_sym
-        end
-      end
-
-      def initialize(engine, collection)
-        @engine     = engine
-        @collection = collection
-      end
-
-      def each
-        to_sql = Visitors::ToSql.new @engine
-
-        @collection.each { |c|
-          c.extend(Value)
-          c.visitor = to_sql
-          yield c
-        }
-      end
-    end
-  end
-end