Return null when window.open blocks a popup.

third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp

Index: third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp
diff --git a/third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp b/third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp
index 176a6376689567713d4f45fe2c10e2f45e7a6160..7640aff78f21e0b9c9c03fed995a059038eb23e8 100644
--- a/third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp
+++ b/third_party/WebKit/Source/bindings/core/v8/custom/V8WindowCustom.cpp
@@ -239,6 +239,7 @@ void V8Window::openMethodCustom(
                                 "Window", info.Holder(), info.GetIsolate());
   if (!BindingSecurity::shouldAllowAccessTo(currentDOMWindow(info.GetIsolate()),
                                             impl, exceptionState)) {
+    v8SetReturnValueNull(info);
     return;
   }
 
@@ -259,8 +260,10 @@ void V8Window::openMethodCustom(
   DOMWindow* openedWindow = toLocalDOMWindow(impl)->open(
       urlString, frameName, windowFeaturesString,
       currentDOMWindow(info.GetIsolate()), enteredDOMWindow(info.GetIsolate()));
-  if (!openedWindow)
+  if (!openedWindow) {
+    v8SetReturnValueNull(info);
     return;
+  }
 
   v8SetReturnValueFast(info, openedWindow, impl);
 }