Don't crash when importing a 404

sky/engine/bindings/core/v8/ScriptController.cpp

Index: sky/engine/bindings/core/v8/ScriptController.cpp
diff --git a/sky/engine/bindings/core/v8/ScriptController.cpp b/sky/engine/bindings/core/v8/ScriptController.cpp
index 38f1942d6e3cb463f692b192789cde3bcdcf677a..e257975a347a1d1f97825fcb19af9bca6dcab051 100644
--- a/sky/engine/bindings/core/v8/ScriptController.cpp
+++ b/sky/engine/bindings/core/v8/ScriptController.cpp
@@ -353,7 +353,10 @@ void ScriptController::executeModuleScript(Document& document, const String& sou
                 String name = link->as();
                 if (!name.isEmpty()) {
                     module.formalDependenciesAndSource.append(v8String(m_isolate, name));
-                    module.resolvedDependencies.append(child->document() ? child->document()->exports().v8Value() : v8Undefined());
+                    v8::Handle<v8::Value> actual = v8::Undefined(m_isolate);
+                    if (child->document())
+                        actual = child->document()->exports().v8Value();
+                    module.resolvedDependencies.append(actual);
                 }
             }
         }