Auto merge of #21399 - gterzian:error_on_placeholder_load, r=jdm

Fire error when placeholder is loaded

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---
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- [ ] `./mach build -d` does not report any errors
- [ ] `./mach test-tidy` does not report any errors
- [ ] These changes fix #21397 (github issue number if applicable).

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- [ ] There are tests for these changes OR
- [ ] These changes do not require tests because _____

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components/script/dom/htmlimageelement.rs

@@ -303,38 +303,43 @@ impl HTMLImageElement {
         document.loader_mut().fetch_async_background(request, action_sender);
     }
 
-    /// Step 14 of https://html.spec.whatwg.org/multipage/#update-the-image-data
+    // Steps common to when an image has been loaded.
+    fn handle_loaded_image(&self, image: Arc<Image>, url: ServoUrl) {
+        self.current_request.borrow_mut().metadata = Some(ImageMetadata {
+            height: image.height,
+            width: image.width
+        });
+        self.current_request.borrow_mut().final_url = Some(url);
+        self.current_request.borrow_mut().image = Some(image);
+        self.current_request.borrow_mut().state = State::CompletelyAvailable;
+        LoadBlocker::terminate(&mut self.current_request.borrow_mut().blocker);
+        // Mark the node dirty
+        self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+    }
+
+    /// Step 24 of https://html.spec.whatwg.org/multipage/#update-the-image-data
     fn process_image_response(&self, image: ImageResponse) {
         // TODO: Handle multipart/x-mixed-replace
         let (trigger_image_load, trigger_image_error) = match (image, self.image_request.get()) {
-            (ImageResponse::Loaded(image, url), ImageRequestPhase::Current) |
+            (ImageResponse::Loaded(image, url), ImageRequestPhase::Current) => {
+                self.handle_loaded_image(image, url);
+                (true, false)
+            },
             (ImageResponse::PlaceholderLoaded(image, url), ImageRequestPhase::Current) => {
-                self.current_request.borrow_mut().metadata = Some(ImageMetadata {
-                    height: image.height,
-                    width: image.width
-                });
-                self.current_request.borrow_mut().final_url = Some(url);
-                self.current_request.borrow_mut().image = Some(image);
-                self.current_request.borrow_mut().state = State::CompletelyAvailable;
-                LoadBlocker::terminate(&mut self.current_request.borrow_mut().blocker);
-                // Mark the node dirty
-                self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
+                self.handle_loaded_image(image, url);
+                (false, true)
+            },
+            (ImageResponse::Loaded(image, url), ImageRequestPhase::Pending) => {
+                self.abort_request(State::Unavailable, ImageRequestPhase::Pending);
+                self.image_request.set(ImageRequestPhase::Current);
+                self.handle_loaded_image(image, url);
                 (true, false)
             },
-            (ImageResponse::Loaded(image, url), ImageRequestPhase::Pending) |
             (ImageResponse::PlaceholderLoaded(image, url), ImageRequestPhase::Pending) => {
                 self.abort_request(State::Unavailable, ImageRequestPhase::Pending);
                 self.image_request.set(ImageRequestPhase::Current);
-                self.current_request.borrow_mut().metadata = Some(ImageMetadata {
-                    height: image.height,
-                    width: image.width
-                });
-                self.current_request.borrow_mut().final_url = Some(url);
-                self.current_request.borrow_mut().image = Some(image);
-                self.current_request.borrow_mut().state = State::CompletelyAvailable;
-                LoadBlocker::terminate(&mut self.current_request.borrow_mut().blocker);
-                self.upcast::<Node>().dirty(NodeDamage::OtherNodeDamage);
-                (true, false)
+                self.handle_loaded_image(image, url);
+                (false, true)
             },
             (ImageResponse::MetadataLoaded(meta), ImageRequestPhase::Current) => {
                 self.current_request.borrow_mut().state = State::PartiallyAvailable;

tests/wpt/mozilla/meta/MANIFEST.json

@@ -13976,6 +13976,12 @@
      {}
     ]
    ],
+   "mozilla/img_placeholder_load.html": [
+    [
+     "/_mozilla/mozilla/img_placeholder_load.html",
+     {}
+    ]
+   ],
    "mozilla/img_width_height.html": [
     [
      "/_mozilla/mozilla/img_width_height.html",
@@ -27043,6 +27049,10 @@
    "e9f1b56ac4c49c146868123a9a73f55c85ae3771",
    "testharness"
   ],
+  "mozilla/img_placeholder_load.html": [
+   "c90b0041a4bc4c255819839cec7265ae65454674",
+   "testharness"
+  ],
   "mozilla/img_width_height.html": [
    "ec68ac34ee2a35aebb38eb297a33a1cd98f5893c",
    "testharness"

tests/wpt/mozilla/tests/mozilla/img_placeholder_load.html

@@ -0,0 +1,21 @@
+<!DOCTYPE HTML>
+<meta charset="utf-8">
+<title>Loading a placeholder image should trigger an error on the img element</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+
+<img>
+
+<script>
+  async_test(function(t) {
+    var img = document.querySelector("img");
+    img.onload = this.step_func_done(function() {
+      assert_unreached("image.onload() was not supposed to be called");
+    });
+    img.onerror = this.step_func_done(function(e) {
+      assert_equals(e.type, "error", "image.onerror() called");
+      t.done();
+    });
+    img.src = "http://whatevertheheckawefawefawe.org/img.gif";
+  });
+</script>