Introduce Response.redirect attribute and add LayoutTest.

third_party/WebKit/Source/modules/fetch/Response.cpp

Index: third_party/WebKit/Source/modules/fetch/Response.cpp
diff --git a/third_party/WebKit/Source/modules/fetch/Response.cpp b/third_party/WebKit/Source/modules/fetch/Response.cpp
index 056f3336fb0b240c790e23f1edb86ed0b4388f41..6b4300cd2726bc285c540370352a76da15f8b218 100644
--- a/third_party/WebKit/Source/modules/fetch/Response.cpp
+++ b/third_party/WebKit/Source/modules/fetch/Response.cpp
@@ -364,6 +364,10 @@ String Response::url() const {
   return url;
 }
 
+bool Response::redirected() const {
+  return m_response->urlList().size() > 1;
+}
+
 unsigned short Response::status() const {
   // "The status attribute's getter must return response's status."
   return m_response->status();