Add missing opener frame null check.

third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp

Index: third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
diff --git a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
index af33c13e628d75502acb4e070440278670413e28..a5328c4c1f3c40a48f012e81b7bd3ded02ef1d1c 100644
--- a/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
+++ b/third_party/WebKit/Source/core/frame/LocalDOMWindow.cpp
@@ -1429,6 +1429,8 @@ PassRefPtrWillBeRawPtr<DOMWindow> LocalDOMWindow::open(const String& urlString,
 {
     if (!isCurrentlyDisplayedInFrame())
         return nullptr;
+    if (!callingWindow->frame())
+        return nullptr;
     Document* activeDocument = callingWindow->document();
     if (!activeDocument)
         return nullptr;