MemoryCache: Enable MemoryCache to have multiple isolated resource maps

Source/core/testing/Internals.cpp

Index: Source/core/testing/Internals.cpp
diff --git a/Source/core/testing/Internals.cpp b/Source/core/testing/Internals.cpp
index c30457f558d67d42be98073b21f6671e1aa142f2..350c8740de6f790b72015796af093e5adca56ac2 100644
--- a/Source/core/testing/Internals.cpp
+++ b/Source/core/testing/Internals.cpp
@@ -354,7 +354,8 @@ bool Internals::isLoadingFromMemoryCache(const String& url)
 {
     if (!contextDocument())
         return false;
-    Resource* resource = memoryCache()->resourceForURL(contextDocument()->completeURL(url));
+    const String cacheIdentifier = contextDocument()->fetcher()->getCacheIdentifier();
+    Resource* resource = memoryCache()->resourceForURL(contextDocument()->completeURL(url), cacheIdentifier);
     return resource && resource->status() == Resource::Cached;
 }