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 6e8f34af4b214b020e4b298aab9c444fecbba63f..e317c2395948ebb1f6ba3f98ef09c30404a81170 100644
--- a/Source/modules/fetch/FetchManager.cpp
+++ b/Source/modules/fetch/FetchManager.cpp
@@ -358,7 +358,7 @@ 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) {
@@ -467,6 +467,8 @@ 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();