Merge pull request #16424 from gregors/remove_dead_code

remove dead file_watcher code

activesupport/lib/active_support/file_watcher.rb

-module ActiveSupport
-  class FileWatcher
-    class Backend
-      def initialize(path, watcher)
-        @watcher = watcher
-        @path    = path
-      end
-
-      def trigger(files)
-        @watcher.trigger(files)
-      end
-    end
-
-    def initialize
-      @regex_matchers = {}
-    end
-
-    def watch(pattern, &block)
-      @regex_matchers[pattern] = block
-    end
-
-    def trigger(files)
-      trigger_files = Hash.new { |h,k| h[k] = Hash.new { |h2,k2| h2[k2] = [] } }
-
-      files.each do |file, state|
-        @regex_matchers.each do |pattern, block|
-          trigger_files[block][state] << file if pattern === file
-        end
-      end
-
-      trigger_files.each do |block, payload|
-        block.call payload
-      end
-    end
-  end
-end