imagebitmap: Remove ImageBitmap from experimental web platform features (#38050)

Enable by default the DOM "ImageBitmap" interface previously gated
behind
"dom.imagebitmap.enabled" preference as experimental web platform
feature.

https://html.spec.whatwg.org/multipage/imagebitmap-and-animations.html#imagebitmap

NOTE: Non blocking non supported functionality:
- vector HTMImageElement, bitmap/vector SVGImageElement
- EXIF image orientation

Testing: Covered by existing WPT tests

Fixes: #34112

Signed-off-by: Andrei Volykhin <andrei.volykhin@gmail.com>

components/config/prefs.rs

@@ -84,7 +84,6 @@ pub struct Preferences {
     pub dom_fontface_enabled: bool,
     pub dom_fullscreen_test: bool,
     pub dom_gamepad_enabled: bool,
-    pub dom_imagebitmap_enabled: bool,
     pub dom_indexeddb_enabled: bool,
     pub dom_intersection_observer_enabled: bool,
     pub dom_microdata_testing_enabled: bool,
@@ -262,7 +261,6 @@ impl Preferences {
             dom_fontface_enabled: false,
             dom_fullscreen_test: false,
             dom_gamepad_enabled: true,
-            dom_imagebitmap_enabled: false,
             dom_indexeddb_enabled: false,
             dom_intersection_observer_enabled: false,
             dom_microdata_testing_enabled: false,

components/script_bindings/webidls/ImageBitmap.webidl

@@ -9,7 +9,7 @@
  * You are granted a license to use, reproduce and create derivative works of this document.
  */
 
-[Exposed=(Window,Worker), Serializable, Transferable, Pref="dom_imagebitmap_enabled"]
+[Exposed=(Window,Worker), Serializable, Transferable]
 interface ImageBitmap {
   readonly attribute unsigned long width;
   readonly attribute unsigned long height;

components/script_bindings/webidls/WindowOrWorkerGlobalScope.webidl

@@ -24,9 +24,7 @@ interface mixin WindowOrWorkerGlobalScope {
   undefined queueMicrotask(VoidFunction callback);
 
   // ImageBitmap
-  [Pref="dom_imagebitmap_enabled"]
   Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image, optional ImageBitmapOptions options = {});
-  [Pref="dom_imagebitmap_enabled"]
   Promise<ImageBitmap> createImageBitmap(ImageBitmapSource image, long sx, long sy, long sw, long sh,
                                          optional ImageBitmapOptions options = {});
 

ports/servoshell/prefs.rs

@@ -589,7 +589,6 @@ pub(crate) fn parse_command_line_arguments(args: Vec<String>) -> ArgumentParsing
         vec![
             "dom_async_clipboard_enabled",
             "dom_fontface_enabled",
-            "dom_imagebitmap_enabled",
             "dom_intersection_observer_enabled",
             "dom_mouse_event_which_enabled",
             "dom_notification_enabled",