Fix Typo existant -> existent [ci skip]

activerecord/CHANGELOG.md

@@ -4,7 +4,7 @@
 
 *   Fixed a bug in `ActiveRecord#sanitize_sql_hash_for_conditions` in which
     `self.class` is an argument to `PredicateBuilder#build_from_hash`
-    causing `PredicateBuilder` to call non-existant method
+    causing `PredicateBuilder` to call non-existent method
     `Class#reflect_on_association`.
 
     *Zach Ohlgren*

activesupport/test/notifications_test.rb

@@ -99,7 +99,7 @@ module Notifications
       @notifier.publish :foo
       @notifier.publish :foo
 
-      @notifier.subscribe("not_existant") do |*args|
+      @notifier.subscribe("not_existent") do |*args|
         @events << ActiveSupport::Notifications::Event.new(*args)
       end
 

railties/test/generators/shared_generator_tests.rb

@@ -77,9 +77,9 @@ module SharedGeneratorTests
   end
 
   def test_template_raises_an_error_with_invalid_path
-    content = capture(:stderr){ run_generator([destination_root, "-m", "non/existant/path"]) }
+    content = capture(:stderr){ run_generator([destination_root, "-m", "non/existent/path"]) }
     assert_match(/The template \[.*\] could not be loaded/, content)
-    assert_match(/non\/existant\/path/, content)
+    assert_match(/non\/existent\/path/, content)
   end
 
   def test_template_is_executed_when_supplied