Remove test dependency on logger

I think logger is only used to figure out which methods need to be made
noops in order to silence webrick during tests.

However, it seems possible to do the same using webrick's builtin logger
and the current method does not seem even correct since it's not
guaranteed that the logger gem and webrick's logger will use the same
methods.

spec/bundler/install/gems/dependency_api_fallback_spec.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative "../../support/silent_logger"
-
 RSpec.describe "gemcutter's dependency API" do
   context "when Gemcutter API takes too long to respond" do
     before do
@@ -11,6 +9,7 @@ RSpec.describe "gemcutter's dependency API" do
       @server_uri = "http://127.0.0.1:#{port}"
 
       require_relative "../../support/artifice/endpoint_timeout"
+      require_relative "../../support/silent_logger"
 
       require "rackup/server"
 

spec/bundler/realworld/gemfile_source_header_spec.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative "../support/silent_logger"
-
 RSpec.describe "fetching dependencies with a mirrored source", realworld: true do
   let(:mirror) { "https://server.example.org" }
   let(:original) { "http://127.0.0.1:#{@port}" }
@@ -38,6 +36,7 @@ RSpec.describe "fetching dependencies with a mirrored source", realworld: true d
     @server_uri = "http://127.0.0.1:#{@port}"
 
     require_relative "../support/artifice/endpoint_mirror_source"
+    require_relative "../support/silent_logger"
 
     require "rackup/server"
 

spec/bundler/realworld/mirror_probe_spec.rb

@@ -1,7 +1,5 @@
 # frozen_string_literal: true
 
-require_relative "../support/silent_logger"
-
 RSpec.describe "fetching dependencies with a not available mirror", realworld: true do
   let(:mirror) { @mirror_uri }
   let(:original) { @server_uri }
@@ -111,6 +109,7 @@ RSpec.describe "fetching dependencies with a not available mirror", realworld: t
     @server_uri = "http://#{host}:#{@server_port}"
 
     require_relative "../support/artifice/endpoint"
+    require_relative "../support/silent_logger"
 
     require "rackup/server"
 

spec/bundler/support/silent_logger.rb

@@ -1,10 +1,10 @@
 # frozen_string_literal: true
 
-require "logger"
+require "webrick"
 module Spec
-  class SilentLogger
-    (::Logger.instance_methods - Object.instance_methods).each do |logger_instance_method|
-      define_method(logger_instance_method) {|*args, &blk| }
+  class SilentLogger < WEBrick::BasicLog
+    def initialize(log_file = nil, level = nil)
+      super(log_file, level || FATAL)
     end
   end
 end

tool/bundler/dev_gems.rb

@@ -13,7 +13,6 @@ gem "rspec-core", "~> 3.12"
 gem "rspec-expectations", "~> 3.12"
 gem "rspec-mocks", "~> 3.12"
 gem "uri", "~> 0.13.0"
-gem "logger", "~> 1.6.5"
 
 group :doc do
   gem "ronn-ng", "~> 0.10.1", platform: :ruby