Revert "Create errors (especially cancellation errors) internally to WebCore, rather"

Source/core/loader/FrameLoader.cpp

Index: Source/core/loader/FrameLoader.cpp
diff --git a/Source/core/loader/FrameLoader.cpp b/Source/core/loader/FrameLoader.cpp
index e895269c1ecafdb193624ff5faff100520f6eee5..2b7adbb2f4b57480aded9a3c3ee37d5b80a4cd26 100644
--- a/Source/core/loader/FrameLoader.cpp
+++ b/Source/core/loader/FrameLoader.cpp
@@ -2323,11 +2323,7 @@ void FrameLoader::receivedMainResourceError(const ResourceError& error)
     // FIXME: Don't want to do this if an entirely new load is going, so should check
     // that both data sources on the frame are either this or nil.
     stop();
-
-    // FIXME: We really ought to be able to just check for isCancellation() here, but there are some
-    // ResourceErrors that setIsCancellation() but aren't created by ResourceError::cancelledError().
-    ResourceError c(ResourceError::cancelledError(KURL()));
-    if (error.errorCode() != c.errorCode() || error.domain() != c.domain())
+    if (m_client->shouldFallBack(error))
         handleFallbackContent();
 
     if (m_state == FrameStateProvisional && m_provisionalDocumentLoader) {
@@ -2596,7 +2592,7 @@ void FrameLoader::requestFromDelegate(ResourceRequest& request, unsigned long& i
     notifier()->dispatchWillSendRequest(m_documentLoader.get(), identifier, newRequest, ResourceResponse());
 
     if (newRequest.isNull())
-        error = ResourceError::cancelledError(request.url());
+        error = cancelledError(request);
     else
         error = ResourceError();
 
@@ -2849,6 +2845,13 @@ void FrameLoader::loadItem(HistoryItem* item, FrameLoadType loadType)
         loadDifferentDocumentItem(item, loadType, MayAttemptCacheOnlyLoadForFormSubmissionItem);
 }
 
+ResourceError FrameLoader::cancelledError(const ResourceRequest& request) const
+{
+    ResourceError error = m_client->cancelledError(request);
+    error.setIsCancellation(true);
+    return error;
+}
+
 void FrameLoader::setTitle(const StringWithDirection& title)
 {
     documentLoader()->setTitle(title);