Bug 1147215 - Add a helper to get the current window with a null check. r=smaug

dom/base/ScriptSettings.cpp

@@ -483,7 +483,7 @@ WarningOnlyErrorReporter(JSContext* aCx, const char* aMessage, JSErrorReport* aR
 {
   MOZ_ASSERT(JSREPORT_IS_WARNING(aRep->flags));
   nsRefPtr<xpc::ErrorReport> xpcReport = new xpc::ErrorReport();
-  nsPIDOMWindow* win = xpc::WindowGlobalOrNull(JS::CurrentGlobalOrNull(aCx));
+  nsPIDOMWindow* win = xpc::CurrentWindowOrNull(aCx);
   xpcReport->Init(aRep, aMessage, nsContentUtils::IsCallerChrome(),
                   win ? win->WindowID() : 0);
   xpcReport->LogToConsole();

js/xpconnect/src/XPCJSRuntime.cpp

@@ -597,6 +597,13 @@ AddonWindowOrNull(JSObject *aObj)
     return WindowOrNull(mainGlobal);
 }
 
+nsGlobalWindow*
+CurrentWindowOrNull(JSContext *cx)
+{
+    JSObject *glob = JS::CurrentGlobalOrNull(cx);
+    return glob ? WindowOrNull(glob) : nullptr;
+}
+
 }
 
 static void

js/xpconnect/src/xpcpublic.h

@@ -469,6 +469,13 @@ WindowGlobalOrNull(JSObject *aObj);
 nsGlobalWindow*
 AddonWindowOrNull(JSObject *aObj);
 
+/**
+ * If |cx| is in a compartment whose global is a window, returns the associated
+ * nsGlobalWindow. Otherwise, returns null.
+ */
+nsGlobalWindow*
+CurrentWindowOrNull(JSContext *cx);
+
 // Error reporter used when there is no associated DOM window on to which to
 // report errors and warnings.
 //