Implement redirect() API for Fetch Response

Source/modules/fetch/Response.cpp

Index: Source/modules/fetch/Response.cpp
diff --git a/Source/modules/fetch/Response.cpp b/Source/modules/fetch/Response.cpp
index 62cd8f2d84c6bfa1412db5e250fa097d53e8ea27..fa619904645df97dd667580f2cbd382ae1163ca9 100644
--- a/Source/modules/fetch/Response.cpp
+++ b/Source/modules/fetch/Response.cpp
@@ -242,6 +242,28 @@ Response* Response::error(ExecutionContext* context)
     return r;
 }
 
+Response* Response::redirect(ExecutionContext* context, const String& url, unsigned short status, ExceptionState& exceptionState)
+{
+    KURL parsedURL = context->completeURL(url);
+    if (!parsedURL.isValid()) {
+        exceptionState.throwTypeError("Failed to parse URL from " + url);
+        return nullptr;
+    }
+
+    if (status != 301 && status != 302 && status != 303 && status != 307 && status != 308) {
+        exceptionState.throwRangeError("Invalid status code");
+        return nullptr;
+    }
+
+    Response* r = new Response(context);
+    r->suspendIfNeeded();
+    r->m_headers->setGuard(Headers::ImmutableGuard);
+    r->m_response->setStatus(status);
+    r->m_response->headerList()->set("Location", parsedURL);
+
+    return r;
+}
+
 String Response::type() const
 {
     // "The type attribute's getter must return response's type."