Allow filename suggestions via a[download] for data URIs

Source/core/html/HTMLAnchorElement.cpp

Index: Source/core/html/HTMLAnchorElement.cpp
diff --git a/Source/core/html/HTMLAnchorElement.cpp b/Source/core/html/HTMLAnchorElement.cpp
index 7f585364663eea2a28813e9b30cf72140c82693f..11c8f4f9ad989999d65d413106842afebdb44838 100644
--- a/Source/core/html/HTMLAnchorElement.cpp
+++ b/Source/core/html/HTMLAnchorElement.cpp
@@ -384,7 +384,7 @@ void HTMLAnchorElement::handleClick(Event* event)
                 request.setHTTPReferrer(Referrer(referrer, document().referrerPolicy()));
         }
 
-        bool isSameOrigin = document().securityOrigin()->canRequest(completedURL);
+        bool isSameOrigin = completedURL.protocolIsData() || document().securityOrigin()->canRequest(completedURL);
         const AtomicString& suggestedName = (isSameOrigin ? fastGetAttribute(downloadAttr) : nullAtom);
 
         frame->loader().client()->loadURLExternally(request, NavigationPolicyDownload, suggestedName);