Should check whether document.settings() is available or not when updating GenericFontFamilySetting…

Source/core/dom/StyleEngine.cpp

Index: Source/core/dom/StyleEngine.cpp
diff --git a/Source/core/dom/StyleEngine.cpp b/Source/core/dom/StyleEngine.cpp
index a7a0c141384487c4ac9552a9ed3d07a68edae30c..52fea5c31f0019cdd4ea19df8022d1be05b01bf1 100644
--- a/Source/core/dom/StyleEngine.cpp
+++ b/Source/core/dom/StyleEngine.cpp
@@ -525,6 +525,10 @@ void StyleEngine::clearFontCache()
 
 void StyleEngine::updateGenericFontFamilySettings()
 {
+    // FIXME: we should not update generic font family settings when
+    // document is inactive.
+    ASSERT(document().isActive());
+
     if (!m_fontSelector)
         return;