Bug 1672303 - part 3: Get rid of "dom.inputevent.datatransfer.enabled" r=smaug

Depends on D94249

Differential Revision: https://phabricator.services.mozilla.com/D94250

dom/webidl/InputEvent.webidl

@@ -36,7 +36,7 @@ dictionary InputEventInit : UIEventInit
 // https://rawgit.com/w3c/input-events/v1/index.html#interface-InputEvent
 partial interface InputEvent
 {
-  [NeedsCallerType, Pref="dom.inputevent.datatransfer.enabled"]
+  [NeedsCallerType]
   readonly attribute DataTransfer? dataTransfer;
   // Enable `getTargetRanges()` only when `beforeinput` event is enabled
   // because this may be used for feature detection of `beforeinput` event
@@ -47,7 +47,6 @@ partial interface InputEvent
 
 partial dictionary InputEventInit
 {
-  [Pref="dom.inputevent.datatransfer.enabled"]
   DataTransfer? dataTransfer = null;
   [Pref="dom.input_events.beforeinput.enabled"]
   sequence<StaticRange> targetRanges = [];

modules/libpref/init/StaticPrefList.yaml

@@ -2036,12 +2036,6 @@
   value: false
   mirror: always
 
-# Is support for InputEvent.dataTransfer enabled?
-- name: dom.inputevent.datatransfer.enabled
-  type: bool
-  value: true
-  mirror: always
-
 # Whether to allow or disallow web apps to cancel `beforeinput` events caused
 # by MozEditableElement#setUserInput() which is used by autocomplete, autofill
 # and password manager.