servo: Merge #17763 - Placed worklets implementation behind a pref (from asajeffrey:script-worklets-pref); r=jdm

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At the moment, worklets are always exposed, even though their spec is still a draft. This PR hides them behind a pref.

---
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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix #17680.
- [X] These changes do not require tests because the existing worklet tests do the job.

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Source-Repo: https://github.com/servo/servo
Source-Revision: 92eeec297bb14f08873aecc04ca3734a37c0478f

--HG--
extra : subtree_source : https%3A//hg.mozilla.org/projects/converted-servo-linear
extra : subtree_revision : d99773ba42509e1186b63fcd82826b0d479b9453

servo/components/script/dom/webidls/CSSStyleValue.webidl

@@ -4,7 +4,7 @@
 
 // https://drafts.css-houdini.org/css-typed-om-1/#cssstylevalue
 // NOTE: should this be exposed to Window?
-[Exposed=(Worklet)]
+[Pref="dom.worklet.enabled", Exposed=(Worklet)]
 interface CSSStyleValue {
     stringifier;
     // static CSSStyleValue? parse(DOMString property, DOMString cssText);

servo/components/script/dom/webidls/PaintRenderingContext2D.webidl

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintrenderingcontext2d
-[Exposed=PaintWorklet]
+[Pref="dom.worklet.enabled", Exposed=PaintWorklet]
 interface PaintRenderingContext2D {
 };
 PaintRenderingContext2D implements CanvasState;

servo/components/script/dom/webidls/PaintSize.webidl

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintsize
-[Exposed=PaintWorklet]
+[Pref="dom.worklet.enabled", Exposed=PaintWorklet]
 interface PaintSize {
     readonly attribute double width;
     readonly attribute double height;

servo/components/script/dom/webidls/PaintWorkletGlobalScope.webidl

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/css-paint-api/#paintworkletglobalscope
-[Global=(Worklet,PaintWorklet), Exposed=PaintWorklet]
+[Global=(Worklet,PaintWorklet), Pref="dom.worklet.enabled", Exposed=PaintWorklet]
 interface PaintWorkletGlobalScope : WorkletGlobalScope {
     [Throws] void registerPaint(DOMString name, VoidFunction paintCtor);
 };

servo/components/script/dom/webidls/StylePropertyMapReadOnly.webidl

@@ -4,7 +4,7 @@
 
 // https://drafts.css-houdini.org/css-typed-om-1/#stylepropertymapreadonly
 // NOTE: should this be exposed to Window?
-[Exposed=(Worklet)]
+[Pref="dom.worklet.enabled", Exposed=(Worklet)]
 interface StylePropertyMapReadOnly {
     CSSStyleValue? get(DOMString property);
     // sequence<CSSStyleValue> getAll(DOMString property);

servo/components/script/dom/webidls/TestWorkletGlobalScope.webidl

@@ -5,7 +5,7 @@
 // This interface is entirely internal to Servo, and should not be accessible to
 // web pages.
 
-[Global=(Worklet,TestWorklet), Exposed=TestWorklet]
+[Global=(Worklet,TestWorklet), Pref="dom.worklet.enabled", Exposed=TestWorklet]
 interface TestWorkletGlobalScope : WorkletGlobalScope {
     void registerKeyValue(DOMString key, DOMString value);
 };

servo/components/script/dom/webidls/Window.webidl

@@ -206,5 +206,5 @@ partial interface Window {
 
 // https://drafts.css-houdini.org/css-paint-api-1/#paint-worklet
 partial interface Window {
-    [SameObject] readonly attribute Worklet paintWorklet;
+    [SameObject, Pref="dom.worklet.enabled"] readonly attribute Worklet paintWorklet;
 };

servo/components/script/dom/webidls/Worklet.webidl

@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 // https://drafts.css-houdini.org/worklets/#worklet
-[Exposed=(Window)]
+[Pref="dom.worklet.enabled", Exposed=(Window)]
 interface Worklet {
     [NewObject] Promise<void> addModule(USVString moduleURL, optional WorkletOptions options);
 };

servo/components/script/dom/webidls/WorkletGlobalScope.webidl

@@ -5,6 +5,6 @@
 // https://drafts.css-houdini.org/worklets/#workletglobalscope
 // TODO: The spec IDL doesn't make this a subclass of EventTarget
 //       https://github.com/whatwg/html/issues/2611
-[Exposed=Worklet]
+[Pref="dom.worklet.enabled", Exposed=Worklet]
 interface WorkletGlobalScope: GlobalScope {
 };