Back out ea2f8a85e0ed (bug 715809) for orange

uriloader/prefetch/nsOfflineCacheUpdate.cpp

@@ -1053,6 +1053,17 @@ nsOfflineManifestItem::OnStartRequest(nsIRequest *aRequest,
         return NS_ERROR_ABORT;
     }
 
+    nsCAutoString contentType;
+    rv = channel->GetContentType(contentType);
+    NS_ENSURE_SUCCESS(rv, rv);
+
+    if (!contentType.EqualsLiteral("text/cache-manifest")) {
+        LOG(("Rejected cache manifest with Content-Type %s (expecting text/cache-manifest)",
+             contentType.get()));
+        mParserState = PARSE_ERROR;
+        return NS_ERROR_ABORT;
+    }
+
     rv = GetOldManifestContentHash(aRequest);
     NS_ENSURE_SUCCESS(rv, rv);