webgpu: Add the dedicated WebGPU task source (#39020)

According to the WebGPU specification there are the dedicated task
source
which is used to queue a global task for a GPUDevice on content
timeline.
https://gpuweb.github.io/gpuweb/#-webgpu-task-source

Tasks on content timeline:
- to fire "uncaptureevent" event
- to resolve GPUDevice.lost promise

Also fixed the "isTrusted" attribute status (false -> true) of the
"uncaptureevent" event by using non JS version of event dispatching.

Testing: No changes in WebGPU CTS expectations
- webgpu:api,operation,uncapturederror:*
- webgpu:api,operation,device,lost:*
- webgpu:api,validation,state,device_lost,destroy:*

Signed-off-by: Andrei Volykhin <volykhin.andrei@huawei.com>
Co-authored-by: Andrei Volykhin <volykhin.andrei@huawei.com>

components/script/dom/globalscope.rs

@@ -3191,7 +3191,6 @@ impl GlobalScope {
         device: WebGPUDevice,
         reason: DeviceLostReason,
         msg: String,
-        can_gc: CanGc,
     ) {
         let reason = match reason {
             DeviceLostReason::Unknown => GPUDeviceLostReason::Unknown,
@@ -3205,7 +3204,7 @@ impl GlobalScope {
             .expect("GPUDevice should still be in devices hashmap")
             .root()
         {
-            device.lose(reason, msg, can_gc);
+            device.lose(reason, msg);
         }
     }
 
@@ -3214,7 +3213,6 @@ impl GlobalScope {
         &self,
         device: WebGPUDevice,
         error: webgpu_traits::Error,
-        can_gc: CanGc,
     ) {
         if let Some(gpu_device) = self
             .gpu_devices
@@ -3222,7 +3220,7 @@ impl GlobalScope {
             .get(&device)
             .and_then(|device| device.root())
         {
-            gpu_device.fire_uncaptured_error(error, can_gc);
+            gpu_device.fire_uncaptured_error(error);
         } else {
             warn!("Recived error for lost GPUDevice!")
         }