Remove PhantomJS-related code from Ruby bindings

It has been deprecated since Selenium 3.6 and is not W3C specification
compliant.

Author: p0deje

rb/lib/selenium/webdriver.rb

@@ -39,7 +39,6 @@ module WebDriver
     autoload :Edge,      'selenium/webdriver/edge'
     autoload :Firefox,   'selenium/webdriver/firefox'
     autoload :IE,        'selenium/webdriver/ie'
-    autoload :PhantomJS, 'selenium/webdriver/phantomjs'
     autoload :Remote,    'selenium/webdriver/remote'
     autoload :Safari,    'selenium/webdriver/safari'
     autoload :Support,   'selenium/webdriver/support'
@@ -54,10 +53,10 @@ def self.root
     # Create a new Driver instance with the correct bridge for the given browser
     #
     # @overload for(browser)
-    #   @param [:ie, :internet_explorer, :edge, :remote, :chrome, :firefox, :ff, :phantomjs, :safari] browser The browser to
+    #   @param [:ie, :internet_explorer, :edge, :remote, :chrome, :firefox, :ff, :safari] browser The browser to
     #     create the driver for
     # @overload for(browser, opts)
-    #   @param [:ie, :internet_explorer, :edge, :remote, :chrome, :firefox, :ff, :phantomjs, :safari] browser The browser to
+    #   @param [:ie, :internet_explorer, :edge, :remote, :chrome, :firefox, :ff, :safari] browser The browser to
     #     create the driver for
     #   @param [Hash] opts Options passed to Driver.new
     #
@@ -68,7 +67,6 @@ def self.root
     # @see Selenium::WebDriver::IE::Driver
     # @see Selenium::WebDriver::Edge::Driver
     # @see Selenium::WebDriver::Chrome::Driver
-    # @see Selenium::WebDriver::PhantomJS::Driver
     # @see Selenium::WebDriver::Safari::Driver
     #
     # @example

rb/lib/selenium/webdriver/common/driver.rb

@@ -48,8 +48,6 @@ def for(browser, opts = {})
             IE::Driver.new(opts)
           when :safari
             Safari::Driver.new(opts)
-          when :phantomjs
-            PhantomJS::Driver.new(opts)
           when :firefox, :ff
             Firefox::Driver.new(opts)
           when :edge

rb/lib/selenium/webdriver/phantomjs.rb

@@ -136,13 +136,6 @@ def internet_explorer(opts = {})
           end
           alias_method :ie, :internet_explorer
 
-          def phantomjs(opts = {})
-            WebDriver.logger.deprecate 'Selenium support for PhantomJS', 'headless Chrome/Firefox or HTMLUnit'
-            new({
-              browser_name: 'phantomjs',
-            }.merge(opts))
-          end
-
           #
           # @api private
           #