Auto merge of #27168 - jdm:gl-fake-context-lost, r=Manishearth

Add stub isContextLost API.

We don't support losing contexts yet, so it's not lying to say that the context is never lost.

---
- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors
- [x] These changes fix #27116
- [x] There are tests for these changes

components/script/dom/webgl2renderingcontext.rs

@@ -1119,6 +1119,11 @@ impl WebGL2RenderingContextMethods for WebGL2RenderingContext {
         self.base.GetContextAttributes()
     }
 
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.13
+    fn IsContextLost(&self) -> bool {
+        self.base.IsContextLost()
+    }
+
     /// https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.14
     fn GetSupportedExtensions(&self) -> Option<Vec<DOMString>> {
         self.base.GetSupportedExtensions()

components/script/dom/webglrenderingcontext.rs

@@ -2319,6 +2319,11 @@ impl WebGLRenderingContextMethods for WebGLRenderingContext {
         })
     }
 
+    // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.13
+    fn IsContextLost(&self) -> bool {
+        false
+    }
+
     // https://www.khronos.org/registry/webgl/specs/latest/1.0/#5.14.14
     fn GetSupportedExtensions(&self) -> Option<Vec<DOMString>> {
         self.extension_manager

components/script/dom/webidls/WebGLRenderingContext.webidl

@@ -470,8 +470,7 @@ interface mixin WebGLRenderingContextBase
     readonly attribute GLsizei drawingBufferHeight;
 
     [WebGLHandlesContextLoss] WebGLContextAttributes? getContextAttributes();
-    // FIXME: https://github.com/servo/servo/issues/15266
-    // [WebGLHandlesContextLoss] boolean isContextLost();
+    [WebGLHandlesContextLoss] boolean isContextLost();
 
     sequence<DOMString>? getSupportedExtensions();
     object? getExtension(DOMString name);