Refactor: support FailedExampleNotification.new(example).

Previously, a second `exception_presenter` argument was required.

Author: myronmarston

lib/rspec/core/notifications.rb

@@ -51,8 +51,7 @@ def self.for(example)
                   FailedExampleNotification
                 end
 
-        exception_presenter = Formatters::ExceptionPresenter::Factory.new(example).build
-        klass.new(example, exception_presenter)
+        klass.new(example)
       end
 
       private_class_method :new
@@ -202,7 +201,7 @@ def fully_formatted(failure_number, colorizer=::RSpec::Core::Formatters::Console
 
     private
 
-      def initialize(example, exception_presenter)
+      def initialize(example, exception_presenter=Formatters::ExceptionPresenter::Factory.new(example).build)
         @exception_presenter = exception_presenter
         super(example)
       end