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
---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [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/canvas_state.rs

@@ -895,12 +895,14 @@ impl CanvasState {
         global: &GlobalScope,
         image: CanvasImageSource,
         mut repetition: DOMString,
-    ) -> Fallible<DomRoot<CanvasPattern>> {
+    ) -> Fallible<Option<DomRoot<CanvasPattern>>> {
         let (image_data, image_size) = match image {
             CanvasImageSource::HTMLImageElement(ref image) => {
-                // https://html.spec.whatwg.org/multipage/#img-error
-                // If the image argument is an HTMLImageElement object that is in the broken state,
-                // then throw an InvalidStateError exception
+                // https://html.spec.whatwg.org/multipage/#check-the-usability-of-the-image-argument
+                if !image.is_usable()? {
+                    return Ok(None);
+                }
+
                 image
                     .get_url()
                     .and_then(|url| {
@@ -933,13 +935,13 @@ impl CanvasState {
         }
 
         if let Ok(rep) = RepetitionStyle::from_str(&repetition) {
-            Ok(CanvasPattern::new(
+            Ok(Some(CanvasPattern::new(
                 global,
                 image_data,
                 image_size,
                 rep,
                 self.is_origin_clean(image),
-            ))
+            )))
         } else {
             Err(Error::Syntax)
         }

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)]