document.open(): gracefully handle exception thrown on window.open access.

Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp

Index: Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp
diff --git a/Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp b/Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp
index 51343476b700591e368564e1d61018fcab25c97b..991d2958ad892404b426cb2b6de10ec7667ceeec 100644
--- a/Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp
+++ b/Source/bindings/v8/custom/V8HTMLDocumentCustom.cpp
@@ -65,6 +65,9 @@ void V8HTMLDocument::openMethodCustom(const v8::FunctionCallbackInfo<v8::Value>&
             v8::Local<v8::Object> global = context->Global();
             // Get the open property of the global object.
             v8::Local<v8::Value> function = global->Get(v8AtomicString(info.GetIsolate(), "open"));
+            // Failed; return without throwing (new) exception.
+            if (function.IsEmpty())
+                return;
             // If the open property is not a function throw a type error.
             if (!function->IsFunction()) {
                 throwTypeError("open is not a function", info.GetIsolate());