Implement Request.context for Fetch API

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 4f0650c0000189d77c29dfb5ff630218d65a5c28..29b2f61ea1404304127a1d3fe565bbd53ff39aa9 100644
--- a/Source/modules/fetch/FetchManager.cpp
+++ b/Source/modules/fetch/FetchManager.cpp
@@ -360,7 +360,7 @@ void FetchManager::Loader::performHTTPFetch(bool corsFlag, bool corsPreflightFla
     // We use ResourceRequest class for HTTPRequest.
     // FIXME: Support body.
     ResourceRequest request(m_request->url());
-    request.setRequestContext(WebURLRequest::RequestContextFetch);
+    request.setRequestContext(m_request->context());
     request.setHTTPMethod(m_request->method());
     const Vector<OwnPtr<FetchHeaderList::Header>>& list = m_request->headerList()->list();
     for (size_t i = 0; i < list.size(); ++i) {
@@ -469,6 +469,8 @@ ScriptPromise FetchManager::fetch(ScriptState* scriptState, FetchRequestData* re
     RefPtrWillBeRawPtr<ScriptPromiseResolver> resolver = ScriptPromiseResolver::create(scriptState);
     ScriptPromise promise = resolver->promise();
 
+    request->setContext(WebURLRequest::RequestContextFetch);
+
     OwnPtrWillBeRawPtr<Loader> ownLoader = Loader::create(m_executionContext, this, resolver.release(), request);
     Loader* loader = m_loaders.add(ownLoader.release()).storedValue->get();
     loader->start();