Remove support for multipart/x-mixed-replace

Source/core/loader/ResourceLoader.cpp

Index: Source/core/loader/ResourceLoader.cpp
diff --git a/Source/core/loader/ResourceLoader.cpp b/Source/core/loader/ResourceLoader.cpp
index 27464c5db5dda0bffe673fe579d62b07827b7186..7cbc6ea67fa4d9263c7901a61c9981ced1351d21 100644
--- a/Source/core/loader/ResourceLoader.cpp
+++ b/Source/core/loader/ResourceLoader.cpp
@@ -322,9 +322,7 @@ void ResourceLoader::didReceiveResponse(ResourceHandle*, const ResourceResponse&
     if (m_options.sendLoadCallbacks == SendCallbacks)
         frameLoader()->notifier()->dispatchDidReceiveResponse(m_documentLoader.get(), m_resource->identifier(), response);
 
-    // FIXME: Main resources have a different set of rules for multipart than images do.
-    // Hopefully we can merge those 2 paths.
-    if (response.isMultipart() && m_resource->type() != CachedResource::MainResource) {
+    if (response.isMultipart()) {
         m_loadingMultipartContent = true;
 
         // We don't count multiParts in a CachedResourceLoader's request count