Remove wrong ASSERT on request instance for fallback in DocumentThreadableLoader

Source/core/loader/DocumentThreadableLoader.cpp

Index: Source/core/loader/DocumentThreadableLoader.cpp
diff --git a/Source/core/loader/DocumentThreadableLoader.cpp b/Source/core/loader/DocumentThreadableLoader.cpp
index 3c7ac1ba4338c819d01683ff92e5acd1a0f3dcb9..012a25c242827bc19a580f40d5232a8431183479 100644
--- a/Source/core/loader/DocumentThreadableLoader.cpp
+++ b/Source/core/loader/DocumentThreadableLoader.cpp
@@ -419,7 +419,11 @@ void DocumentThreadableLoader::handleResponse(unsigned long identifier, const Re
         return;
     }
 
-    ASSERT(!m_fallbackRequestForServiceWorker);
+    // Here, it's possible that |m_fallbackRequestForServiceWorker| is set.
+    // This means the document was controlled by the ServiceWorker but the
+    // browser process didn't forward the request to the ServiceWorker for
+    // some reason.
+    m_fallbackRequestForServiceWorker = nullptr;
 
     if (!m_sameOriginRequest && m_options.crossOriginRequestPolicy == UseAccessControl) {
         String accessControlErrorDescription;