Bug 1184647. Cloning an image should ensure that the clone tries to load the src, if any. r=smaug

dom/html/HTMLImageElement.cpp

@@ -800,10 +800,30 @@ HTMLImageElement::GetNaturalWidth(uint32_t* aNaturalWidth)
 nsresult
 HTMLImageElement::CopyInnerTo(Element* aDest)
 {
-  if (aDest->OwnerDoc()->IsStaticDocument()) {
-    CreateStaticImageClone(static_cast<HTMLImageElement*>(aDest));
+  bool destIsStatic = aDest->OwnerDoc()->IsStaticDocument();
+  auto dest = static_cast<HTMLImageElement*>(aDest);
+  if (destIsStatic) {
+    CreateStaticImageClone(dest);
   }
-  return nsGenericHTMLElement::CopyInnerTo(aDest);
+
+  nsresult rv = nsGenericHTMLElement::CopyInnerTo(aDest);
+  if (NS_FAILED(rv)) {
+    return rv;
+  }
+
+  if (!destIsStatic) {
+    // In SetAttr (called from nsGenericHTMLElement::CopyInnerTo), dest skipped
+    // doing the image load because we passed in false for aNotify.  But we
+    // really do want it to do the load, so set it up to happen once the cloning
+    // reaches a stable state.
+    if (!dest->InResponsiveMode() &&
+        dest->HasAttr(kNameSpaceID_None, nsGkAtoms::src)) {
+      nsContentUtils::AddScriptRunner(
+        NS_NewRunnableMethod(dest, &HTMLImageElement::MaybeLoadImage));
+    }
+  }
+
+  return NS_OK;
 }
 
 CORSMode