MemoryCache: Enable MemoryCache to have multiple isolated resource maps

Source/core/loader/ImageLoader.cpp

Index: Source/core/loader/ImageLoader.cpp
diff --git a/Source/core/loader/ImageLoader.cpp b/Source/core/loader/ImageLoader.cpp
index efb25bdab2b1f03caac65033c557558d6dc2e269..7d4b10d2d172ea89a7f60307748411d33eb10ddb 100644
--- a/Source/core/loader/ImageLoader.cpp
+++ b/Source/core/loader/ImageLoader.cpp
@@ -365,7 +365,7 @@ bool ImageLoader::shouldLoadImmediately(const KURL& url, LoadType loadType) cons
         || isHTMLObjectElement(m_element)
         || isHTMLEmbedElement(m_element)
         || url.protocolIsData()
-        || memoryCache()->resourceForURL(url)
+        || memoryCache()->resourceForURL(url, m_element->document().fetcher()->getCacheIdentifier())
         || loadType == ForceLoadImmediately);
 }