Prefetch @import files from CSS files.

Source/core/fetch/CSSStyleSheetResource.cpp

Index: Source/core/fetch/CSSStyleSheetResource.cpp
diff --git a/Source/core/fetch/CSSStyleSheetResource.cpp b/Source/core/fetch/CSSStyleSheetResource.cpp
index 8f16d80268d5cc8fc9b33257924e3f7d6c156958..a8374d78a2b29bce4eb637c92a0ea4299e4aa936 100644
--- a/Source/core/fetch/CSSStyleSheetResource.cpp
+++ b/Source/core/fetch/CSSStyleSheetResource.cpp
@@ -99,6 +99,16 @@ void CSSStyleSheetResource::checkNotify()
     m_decodedSheetText = String();
 }
 
+void CSSStyleSheetResource::appendData(const char* data, int length)
+{
+    Resource::appendData(data, length);
+
+    ResourcePtr<CSSStyleSheetResource> protect(this);
+    ResourceClientWalker<StyleSheetResourceClient> walker(m_clients);
+    while (StyleSheetResourceClient* client = walker.next())
+        client->dataReceived(this);
+}
+
 bool CSSStyleSheetResource::isSafeToUnlock() const
 {
     return m_data->hasOneRef();