Auto merge of #25710 - pylbrecht:pattern.incomplete, r=jdm

Make CanvasRenderingContext2D.createPattern() return null for incomplete images

<!-- Please describe your changes on the following line: -->
`createPattern()` should return `null` if the passed `image` argument is not usable.

References:
- https://html.spec.whatwg.org/multipage/canvas.html#dom-context-2d-createpattern
- https://html.spec.whatwg.org/multipage/canvas.html#check-the-usability-of-the-image-argument
---
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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 part of #25331

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- [x] There are tests for these changes

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components/script/dom/canvasrenderingcontext2d.rs

@@ -566,7 +566,7 @@ impl CanvasRenderingContext2DMethods for CanvasRenderingContext2D {
         &self,
         image: CanvasImageSource,
         repetition: DOMString,
-    ) -> Fallible<DomRoot<CanvasPattern>> {
+    ) -> Fallible<Option<DomRoot<CanvasPattern>>> {
         self.canvas_state
             .borrow()
             .create_pattern(&self.global(), image, repetition)

components/script/dom/offscreencanvasrenderingcontext2d.rs

@@ -210,7 +210,7 @@ impl OffscreenCanvasRenderingContext2DMethods for OffscreenCanvasRenderingContex
         &self,
         image: CanvasImageSource,
         repetition: DOMString,
-    ) -> Fallible<DomRoot<CanvasPattern>> {
+    ) -> Fallible<Option<DomRoot<CanvasPattern>>> {
         self.canvas_state
             .borrow()
             .create_pattern(&self.global(), image, repetition)

components/script/dom/paintrenderingcontext2d.rs

@@ -340,7 +340,7 @@ impl PaintRenderingContext2DMethods for PaintRenderingContext2D {
         &self,
         image: CanvasImageSource,
         repetition: DOMString,
-    ) -> Fallible<DomRoot<CanvasPattern>> {
+    ) -> Fallible<Option<DomRoot<CanvasPattern>>> {
         self.context.CreatePattern(image, repetition)
     }
 

components/script/dom/webidls/CanvasRenderingContext2D.webidl

@@ -93,7 +93,7 @@ interface mixin CanvasFillStrokeStyles {
   [Throws]
   CanvasGradient createRadialGradient(double x0, double y0, double r0, double x1, double y1, double r1);
   [Throws]
-  CanvasPattern createPattern(CanvasImageSource image, [TreatNullAs=EmptyString] DOMString repetition);
+  CanvasPattern? createPattern(CanvasImageSource image, [TreatNullAs=EmptyString] DOMString repetition);
 };
 
 [Exposed=(PaintWorklet, Window, Worker)]