--- a/dom/html/HTMLImageElement.cpp
+++ b/dom/html/HTMLImageElement.cpp
@@ -80,30 +80,35 @@ namespace dom {
 // Calls LoadSelectedImage on host element unless it has been superseded or
 // canceled -- this is the synchronous section of "update the image data".
 // https://html.spec.whatwg.org/multipage/embedded-content.html#update-the-image-data
 class ImageLoadTask : public nsRunnable
 {
 public:
   explicit ImageLoadTask(HTMLImageElement *aElement) :
     mElement(aElement)
-  {}
+  {
+    mDocument = aElement->OwnerDoc();
+    mDocument->BlockOnload();
+  }
 
   NS_IMETHOD Run()
   {
     if (mElement->mPendingImageLoadTask == this) {
       mElement->mPendingImageLoadTask = nullptr;
       mElement->LoadSelectedImage(true, true);
     }
+    mDocument->UnblockOnload(false);
     return NS_OK;
   }
 
 private:
   ~ImageLoadTask() {}
   nsRefPtr<HTMLImageElement> mElement;
+  nsCOMPtr<nsIDocument> mDocument;
 };
 
 HTMLImageElement::HTMLImageElement(already_AddRefed<mozilla::dom::NodeInfo>& aNodeInfo)
   : nsGenericHTMLElement(aNodeInfo)
   , mForm(nullptr)
 {
   // We start out broken
   AddStatesSilently(NS_EVENT_STATE_BROKEN);

--- a/dom/html/test/mochitest.ini
+++ b/dom/html/test/mochitest.ini
@@ -589,10 +589,9 @@ skip-if = buildapp == 'b2g' || e10s
 skip-if = (buildapp == 'b2g' && toolkit != 'gonk') || e10s #Bug 931116, b2g desktop specific, initial triage
 support-files = file_bug871161-1.html file_bug871161-2.html
 [test_bug1013316.html]
 [test_hash_encoded.html]
 [test_bug1081037.html]
 [test_window_open_close.html]
 skip-if = buildapp == 'b2g' # bug 1129014
 [test_img_complete.html]
-[test_viewport_resize.html]
-skip-if = os == 'win' || os == 'mac' # bug 1163911
\ No newline at end of file
+[test_viewport_resize.html]
\ No newline at end of file