navigator.vibrate() crash avoidance when in a detached state.

Source/modules/vibration/NavigatorVibration.cpp

Index: Source/modules/vibration/NavigatorVibration.cpp
diff --git a/Source/modules/vibration/NavigatorVibration.cpp b/Source/modules/vibration/NavigatorVibration.cpp
index c4a16ffbd122ea0065c500d8efac0e779dbe0cd3..6a8b5d31b8c281911606cc162c9b7cf7b0e90914 100644
--- a/Source/modules/vibration/NavigatorVibration.cpp
+++ b/Source/modules/vibration/NavigatorVibration.cpp
@@ -145,6 +145,9 @@ bool NavigatorVibration::vibrate(Navigator& navigator, unsigned time)
 
 bool NavigatorVibration::vibrate(Navigator& navigator, const VibrationPattern& pattern)
 {
+    if (!navigator.frame())
+        return false;
+
     Page* page = navigator.frame()->page();
     if (!page)
         return false;