Bug 1223258 - Fix -Wunreachable-code warnings in widget. r=masayuki

widget/tests/TestAppShellSteadyState.cpp:397:5: warning: code will never be executed [-Wunreachable-code]
widget\widgetutils.cpp(95) : warning C4702: unreachable code
widget\mouseevents.h(97) : warning C4702: unreachable code
widget\textevents.h(492) : warning C4702: unreachable code

widget/MouseEvents.h

@@ -94,7 +94,6 @@ public:
   virtual WidgetEvent* Duplicate() const override
   {
     MOZ_CRASH("WidgetMouseEventBase must not be most-subclass");
-    return nullptr;
   }
 
   /// The possible related target

widget/TextEvents.h

@@ -489,7 +489,6 @@ public:
     NS_ASSERTION(!IsAllowedToDispatchDOMEvent(),
       "WidgetQueryContentEvent needs to support Duplicate()");
     MOZ_CRASH("WidgetQueryContentEvent doesn't support Duplicate()");
-    return nullptr;
   }
 
   void InitForQueryTextContent(uint32_t aOffset, uint32_t aLength,

widget/WidgetUtils.cpp

@@ -92,7 +92,6 @@ nsIntRect RotateRect(nsIntRect aRect,
                        aRect.height, aRect.width);
     default:
       MOZ_CRASH("Unknown rotation");
-      return aRect;
   }
 }
 

widget/tests/TestAppShellSteadyState.cpp

@@ -391,8 +391,7 @@ Test4Internal(nsIAppShell* aAppShell)
 #ifndef XP_WIN
   // Not sure how to test on other platforms.
   return false;
-#endif
-
+#else
   nsCOMPtr<nsIAppShellService> appService =
     do_GetService(NS_APPSHELLSERVICE_CONTRACTID);
   if (!appService) {
@@ -437,6 +436,7 @@ Test4Internal(nsIAppShell* aAppShell)
   }
 
   return true;
+#endif
 }
 
 void