diff --git a/components/script/document_loader.rs b/components/script/document_loader.rs
index a4ce36a2f57..611c469fa2d 100644
--- a/components/script/document_loader.rs
+++ b/components/script/document_loader.rs
@@ -120,7 +120,7 @@ impl DocumentLoader {
     }
 
     /// Initiate a new fetch that does not block the document load event.
-    pub fn fetch_async_background(&mut self,
+    pub fn fetch_async_background(&self,
                                   request: RequestInit,
                                   fetch_target: IpcSender<FetchResponseMsg>) {
         self.resource_threads.sender().send(CoreResourceMsg::Fetch(request, fetch_target)).unwrap();
diff --git a/components/script/dom/document.rs b/components/script/dom/document.rs
index e71961882e4..29d7227dee9 100644
--- a/components/script/dom/document.rs
+++ b/components/script/dom/document.rs
@@ -108,7 +108,7 @@ use net_traits::response::HttpsState;
 use num_traits::ToPrimitive;
 use script_layout_interface::message::{Msg, ReflowQueryType};
 use script_runtime::{CommonScriptMsg, ScriptThreadEventCategory};
-use script_thread::{MainThreadScriptMsg, Runnable};
+use script_thread::{MainThreadScriptMsg, Runnable, ScriptThread};
 use script_traits::{AnimationState, CompositorEvent, DocumentActivity};
 use script_traits::{MouseButton, MouseEventType, MozBrowserEvent};
 use script_traits::{MsDuration, ScriptMsg as ConstellationMsg, TouchpadPressurePhase};
@@ -1641,17 +1641,26 @@ impl Document {
         // Step 5 can be found in asap_script_loaded and
         // asap_in_order_script_loaded.
 
+        let loader = self.loader.borrow();
+        if loader.is_blocked() || loader.events_inhibited() {
+            // Step 6.
+            return;
+        }
+
+        ScriptThread::mark_document_with_no_blocked_loads(self);
+    }
+
+    // https://html.spec.whatwg.org/multipage/#the-end
+    pub fn maybe_queue_document_completion(&self) {
         if self.loader.borrow().is_blocked() {
             // Step 6.
             return;
         }
 
-        // The rest will ever run only once per document.
-        if self.loader.borrow().events_inhibited() {
-            return;
-        }
+        assert!(!self.loader.borrow().events_inhibited());
         self.loader.borrow_mut().inhibit_events();
 
+        // The rest will ever run only once per document.
         // Step 7.
         debug!("Document loads are complete.");
         let handler = box DocumentProgressHandler::new(Trusted::new(self));
diff --git a/components/script/dom/htmlimageelement.rs b/components/script/dom/htmlimageelement.rs
index 8f7497c55ac..ecf63720845 100644
--- a/components/script/dom/htmlimageelement.rs
+++ b/components/script/dom/htmlimageelement.rs
@@ -47,6 +47,8 @@ use network_listener::{NetworkListener, PreInvoke};
 use num_traits::ToPrimitive;
 use script_thread::Runnable;
 use servo_url::ServoUrl;
+use std::cell::Cell;
+use std::default::Default;
 use std::i32;
 use std::sync::{Arc, Mutex};
 use style::attr::{AttrValue, LengthOrPercentageOrAuto};
@@ -76,6 +78,7 @@ pub struct HTMLImageElement {
     htmlelement: HTMLElement,
     current_request: DOMRefCell<ImageRequest>,
     pending_request: DOMRefCell<ImageRequest>,
+    generation: Cell<u32>,
 }
 
 impl HTMLImageElement {
@@ -87,14 +90,16 @@ impl HTMLImageElement {
 struct ImageResponseHandlerRunnable {
     element: Trusted<HTMLImageElement>,
     image: ImageResponse,
+    generation: u32,
 }
 
 impl ImageResponseHandlerRunnable {
-    fn new(element: Trusted<HTMLImageElement>, image: ImageResponse)
+    fn new(element: Trusted<HTMLImageElement>, image: ImageResponse, generation: u32)
            -> ImageResponseHandlerRunnable {
         ImageResponseHandlerRunnable {
             element: element,
             image: image,
+            generation: generation,
         }
     }
 }
@@ -104,35 +109,29 @@ impl Runnable for ImageResponseHandlerRunnable {
 
     fn handler(self: Box<Self>) {
         let element = self.element.root();
-        element.process_image_response(self.image);
+        // Ignore any image response for a previous request that has been discarded.
+        if element.generation.get() == self.generation {
+            element.process_image_response(self.image);
+        }
     }
 }
 
 /// The context required for asynchronously loading an external image.
 struct ImageContext {
-    /// The element that initiated the request.
-    elem: Trusted<HTMLImageElement>,
-    /// The initial URL requested.
-    url: ServoUrl,
+    /// A handle with which to communicate with the image cache.
+    image_cache: ImageCacheThread,
     /// Indicates whether the request failed, and why
     status: Result<(), NetworkError>,
     /// The cache ID for this request.
     id: PendingImageId,
 }
 
-impl ImageContext {
-    fn image_cache(&self) -> ImageCacheThread {
-        let elem = self.elem.root();
-        window_from_node(&*elem).image_cache_thread().clone()
-    }
-}
-
 impl FetchResponseListener for ImageContext {
     fn process_request_body(&mut self) {}
     fn process_request_eof(&mut self) {}
 
     fn process_response(&mut self, metadata: Result<FetchMetadata, NetworkError>) {
-        self.image_cache().notify_pending_response(
+        self.image_cache.notify_pending_response(
             self.id,
             FetchResponseMsg::ProcessResponse(metadata.clone()));
 
@@ -156,19 +155,16 @@ impl FetchResponseListener for ImageContext {
 
     fn process_response_chunk(&mut self, payload: Vec<u8>) {
         if self.status.is_ok() {
-            self.image_cache().notify_pending_response(
+            self.image_cache.notify_pending_response(
                 self.id,
                 FetchResponseMsg::ProcessResponseChunk(payload));
         }
     }
 
     fn process_response_eof(&mut self, response: Result<(), NetworkError>) {
-        let elem = self.elem.root();
-        let document = document_from_node(&*elem);
-        let image_cache = self.image_cache();
-        image_cache.notify_pending_response(self.id,
-                                            FetchResponseMsg::ProcessResponseEOF(response));
-        document.finish_load(LoadType::Image(self.url.clone()));
+        self.image_cache.notify_pending_response(
+            self.id,
+            FetchResponseMsg::ProcessResponseEOF(response));
     }
 }
 
@@ -197,11 +193,12 @@ impl HTMLImageElement {
             let window = window_from_node(elem);
             let task_source = window.networking_task_source();
             let wrapper = window.get_runnable_wrapper();
+            let generation = elem.generation.get();
             ROUTER.add_route(responder_receiver.to_opaque(), box move |message| {
                 // Return the image via a message to the script thread, which marks the element
                 // as dirty and triggers a reflow.
                 let runnable = ImageResponseHandlerRunnable::new(
-                    trusted_node.clone(), message.to().unwrap());
+                    trusted_node.clone(), message.to().unwrap(), generation);
                 let _ = task_source.queue_with_wrapper(box runnable, &wrapper);
             });
 
@@ -243,8 +240,7 @@ impl HTMLImageElement {
         let window = window_from_node(self);
 
         let context = Arc::new(Mutex::new(ImageContext {
-            elem: Trusted::new(self),
-            url: img_url.clone(),
+            image_cache: window.image_cache_thread().clone(),
             status: Ok(()),
             id: id,
         }));
@@ -267,7 +263,9 @@ impl HTMLImageElement {
             .. RequestInit::default()
         };
 
-        document.fetch_async(LoadType::Image(img_url), request, action_sender);
+        // This is a background load because the load blocker already fulfills the
+        // purpose of delaying the document's load event.
+        document.loader().fetch_async_background(request, action_sender);
     }
 
     fn process_image_response(&self, image: ImageResponse) {
@@ -299,7 +297,9 @@ impl HTMLImageElement {
             self.upcast::<EventTarget>().fire_event(atom!("error"));
         }
 
-        LoadBlocker::terminate(&mut self.current_request.borrow_mut().blocker);
+        if trigger_image_load || trigger_image_error {
+            LoadBlocker::terminate(&mut self.current_request.borrow_mut().blocker);
+        }
 
         // Trigger reflow
         let window = window_from_node(self);
@@ -309,6 +309,9 @@ impl HTMLImageElement {
     /// Makes the local `image` member match the status of the `src` attribute and starts
     /// prefetching the image. This method must be called after `src` is changed.
     fn update_image(&self, value: Option<(DOMString, ServoUrl)>) {
+        // Force any in-progress request to be ignored.
+        self.generation.set(self.generation.get() + 1);
+
         let document = document_from_node(self);
         let window = document.window();
         match value {
@@ -381,6 +384,7 @@ impl HTMLImageElement {
                 metadata: None,
                 blocker: None,
             }),
+            generation: Default::default(),
         }
     }
 
@@ -622,6 +626,15 @@ impl VirtualMethods for HTMLImageElement {
         Some(self.upcast::<HTMLElement>() as &VirtualMethods)
     }
 
+    fn adopting_steps(&self, old_doc: &Document) {
+        self.super_type().unwrap().adopting_steps(old_doc);
+
+        let elem = self.upcast::<Element>();
+        let document = document_from_node(self);
+        self.update_image(Some((elem.get_string_attribute(&local_name!("src")),
+                                document.base_url())));
+    }
+
     fn attribute_mutated(&self, attr: &Attr, mutation: AttributeMutation) {
         self.super_type().unwrap().attribute_mutated(attr, mutation);
         match attr.local_name() {
diff --git a/components/script/script_thread.rs b/components/script/script_thread.rs
index 192923294a6..e877e904ceb 100644
--- a/components/script/script_thread.rs
+++ b/components/script/script_thread.rs
@@ -483,6 +483,10 @@ pub struct ScriptThread {
 
     /// A handle to the webvr thread, if available
     webvr_thread: Option<IpcSender<WebVRMsg>>,
+
+    /// A list of pipelines containing documents that finished loading all their blocking
+    /// resources during a turn of the event loop.
+    docs_with_no_blocking_loads: DOMRefCell<HashSet<JS<Document>>>,
 }
 
 /// In the event of thread panic, all data on the stack runs its destructor. However, there
@@ -567,6 +571,15 @@ impl ScriptThreadFactory for ScriptThread {
 }
 
 impl ScriptThread {
+    pub fn mark_document_with_no_blocked_loads(doc: &Document) {
+        SCRIPT_THREAD_ROOT.with(|root| {
+            let script_thread = unsafe { &*root.get().unwrap() };
+            script_thread.docs_with_no_blocking_loads
+                .borrow_mut()
+                .insert(JS::from_ref(doc));
+        })
+    }
+
     pub fn invoke_perform_a_microtask_checkpoint() {
         SCRIPT_THREAD_ROOT.with(|root| {
             let script_thread = unsafe { &*root.get().unwrap() };
@@ -704,7 +717,9 @@ impl ScriptThread {
 
             layout_to_constellation_chan: state.layout_to_constellation_chan,
 
-            webvr_thread: state.webvr_thread
+            webvr_thread: state.webvr_thread,
+
+            docs_with_no_blocking_loads: Default::default(),
         }
     }
 
@@ -885,6 +900,15 @@ impl ScriptThread {
             }
         }
 
+        {
+            // https://html.spec.whatwg.org/multipage/#the-end step 6
+            let mut docs = self.docs_with_no_blocking_loads.borrow_mut();
+            for document in docs.iter() {
+                document.maybe_queue_document_completion();
+            }
+            docs.clear();
+        }
+
         // https://html.spec.whatwg.org/multipage/#event-loop-processing-model step 7.12
 
         // Issue batched reflows on any pages that require it (e.g. if images loaded)
diff --git a/components/script_plugins/unrooted_must_root.rs b/components/script_plugins/unrooted_must_root.rs
index ad74f6c4b8f..c62796b7a90 100644
--- a/components/script_plugins/unrooted_must_root.rs
+++ b/components/script_plugins/unrooted_must_root.rs
@@ -54,7 +54,8 @@ fn is_unrooted_ty(cx: &LateContext, ty: &ty::TyS, in_new_function: bool) -> bool
                         || match_def_path(cx, did.did, &["core", "slice", "Iter"])
                         || match_def_path(cx, did.did, &["std", "collections", "hash", "map", "Entry"])
                         || match_def_path(cx, did.did, &["std", "collections", "hash", "map", "OccupiedEntry"])
-                        || match_def_path(cx, did.did, &["std", "collections", "hash", "map", "VacantEntry"]) {
+                        || match_def_path(cx, did.did, &["std", "collections", "hash", "map", "VacantEntry"])
+                        || match_def_path(cx, did.did, &["std", "collections", "hash", "set", "Iter"]) {
                     // Structures which are semantically similar to an &ptr.
                     false
                 } else if did.is_box() && in_new_function {
diff --git a/tests/wpt/metadata/MANIFEST.json b/tests/wpt/metadata/MANIFEST.json
index b7a485acf49..975eb852e8f 100644
--- a/tests/wpt/metadata/MANIFEST.json
+++ b/tests/wpt/metadata/MANIFEST.json
@@ -8337,6 +8337,18 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-img-element/document-adopt-base-url.html": [
+    [
+     "/html/semantics/embedded-content/the-img-element/document-adopt-base-url.html",
+     [
+      [
+       "/html/semantics/embedded-content/the-img-element/document-base-url-ref.html",
+       "=="
+      ]
+     ],
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-img-element/document-base-url.html": [
     [
      "/html/semantics/embedded-content/the-img-element/document-base-url.html",
@@ -93287,6 +93299,12 @@
      {}
     ]
    ],
+   "html/semantics/embedded-content/the-img-element/delay-load-event.html": [
+    [
+     "/html/semantics/embedded-content/the-img-element/delay-load-event.html",
+     {}
+    ]
+   ],
    "html/semantics/embedded-content/the-img-element/environment-changes/viewport-change.html": [
     [
      "/html/semantics/embedded-content/the-img-element/environment-changes/viewport-change.html",
@@ -176314,6 +176332,14 @@
    "bdbfbe9a5908c6233bd7b9697a0762bd2e0f6ede",
    "testharness"
   ],
+  "html/semantics/embedded-content/the-img-element/delay-load-event.html": [
+   "e4782535af755b29864fd3de67bbdd0de13f19d7",
+   "testharness"
+  ],
+  "html/semantics/embedded-content/the-img-element/document-adopt-base-url.html": [
+   "a4b542eb344cca6bdcceceb3aa7006e900f5400f",
+   "reftest"
+  ],
   "html/semantics/embedded-content/the-img-element/document-base-url-ref.html": [
    "add78257076d22891334b93c8072d098ace9b6eb",
    "support"
diff --git a/tests/wpt/mozilla/meta/MANIFEST.json b/tests/wpt/mozilla/meta/MANIFEST.json
index 8fdbc6e596e..38d378f9e93 100644
--- a/tests/wpt/mozilla/meta/MANIFEST.json
+++ b/tests/wpt/mozilla/meta/MANIFEST.json
@@ -12892,6 +12892,12 @@
      {}
     ]
    ],
+   "mozilla/img_multiple_request.html": [
+    [
+     "/_mozilla/mozilla/img_multiple_request.html",
+     {}
+    ]
+   ],
    "mozilla/img_width_height.html": [
     [
      "/_mozilla/mozilla/img_width_height.html",
@@ -25375,6 +25381,10 @@
    "3c4f36abed83367c851d943b1f25b8394de6fe75",
    "testharness"
   ],
+  "mozilla/img_multiple_request.html": [
+   "0a6263ad87c9b3307f2dc694747b094a0517b79b",
+   "testharness"
+  ],
   "mozilla/img_width_height.html": [
    "37a04735261a6d2b36c3d529ce81eda46ed6967e",
    "testharness"
diff --git a/tests/wpt/mozilla/tests/mozilla/img_multiple_request.html b/tests/wpt/mozilla/tests/mozilla/img_multiple_request.html
new file mode 100644
index 00000000000..df625a2bc33
--- /dev/null
+++ b/tests/wpt/mozilla/tests/mozilla/img_multiple_request.html
@@ -0,0 +1,25 @@
+<html>
+<head>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<script>
+    async_test(function(t) {
+        var i = new Image();
+        i.src = "2x2.png";
+        i.src = "2x2.png";
+        i.onload = t.step_func(function() {
+            i.onload = this.unreached_func("Load event for aborted request.");
+            t.step_timeout(t.step_func_done(), 100);
+        });
+    }, "Multiple requests for the same URL do not trigger multiple load events.");
+
+    async_test(function(t) {
+        var i = new Image();
+        i.src = "test.png";
+        i.src = "2x2.png";
+        i.onload = t.step_func(function() {
+            i.onload = this.unreached_func("Load event for aborted request.");
+            t.step_timeout(t.step_func_done(), 100);
+        });
+    }, "Multiple requests for different URL do not trigger multiple load events.");
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/delay-load-event.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/delay-load-event.html
new file mode 100644
index 00000000000..c67074a40d8
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/delay-load-event.html
@@ -0,0 +1,17 @@
+<html>
+<head>
+<title>Image element delays window's load event</title>
+<script src="/resources/testharness.js"></script>
+<script src="/resources/testharnessreport.js"></script>
+<img src="resources/cat.jpg?pipe=trickle(d2)">
+<script>
+    async_test(function(t) {
+        var saw_img_load = false;
+        document.querySelector('img').onload = t.step_func(function() {
+            saw_img_load = true;
+        });
+        addEventListener('load', t.step_func_done(function() {
+            assert_true(saw_img_load);
+        }));
+    });
+</script>
diff --git a/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/document-adopt-base-url.html b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/document-adopt-base-url.html
new file mode 100644
index 00000000000..ea63114d570
--- /dev/null
+++ b/tests/wpt/web-platform-tests/html/semantics/embedded-content/the-img-element/document-adopt-base-url.html
@@ -0,0 +1,14 @@
+<!DOCTYPE HTML>
+<meta charset="utf-8">
+<title>Document base URL adopted img test</title>
+<link rel="help" href="https://html.spec.whatwg.org/multipage/#the-img-element" />
+<link rel="match" href="document-base-url-ref.html">
+<base href="resources/" />
+<iframe></iframe>
+<script>
+  var iframe = document.querySelector('iframe');
+  var i = iframe.contentDocument.createElement('img');
+  i.src = "cat.jpg";
+  document.body.appendChild(i);
+  iframe.remove();
+</script>