[Fetch] Disable no-cors in non-serviceworker

Source/modules/fetch/FetchManager.cpp

Index: Source/modules/fetch/FetchManager.cpp
diff --git a/Source/modules/fetch/FetchManager.cpp b/Source/modules/fetch/FetchManager.cpp
index 602a217f21f10511716d567cbb899fa510112f2a..5c72ea51574515699a59d3977508d7a382fa516f 100644
--- a/Source/modules/fetch/FetchManager.cpp
+++ b/Source/modules/fetch/FetchManager.cpp
@@ -170,6 +170,12 @@ void FetchManager::Loader::didFailRedirectCheck()
 
 void FetchManager::Loader::start()
 {
+    if (!executionContext()->isServiceWorkerGlobalScope()
+        && m_request->mode() == WebURLRequest::FetchRequestModeNoCORS) {
+        performNetworkError("no-cors is disabled for non-serviceworker.");
+        return;
+    }
+
     // "1. If |request|'s url contains a Known HSTS Host, modify it per the
     // requirements of the 'URI [sic] Loading and Port Mapping' chapter of HTTP
     // Strict Transport Security."