Bug 1318004 - Use C++11's override and remove virtual where applicable. r=Ehsan

MozReview-Commit-ID: H9tAe0YN1tx

toolkit/components/osfile/NativeOSFileInternals.cpp

@@ -741,7 +741,7 @@ public:
     , mResult(new TypedArrayResult(TimeStamp::Now()))
   { }
 
-  ~DoReadToTypedArrayEvent() {
+  ~DoReadToTypedArrayEvent() override {
     // If AbstractReadEvent::Run() has bailed out, we may need to cleanup
     // mResult, which is main-thread only data
     if (!mResult) {
@@ -778,7 +778,7 @@ public:
     , mResult(new StringResult(TimeStamp::Now()))
   { }
 
-  ~DoReadToStringEvent() {
+  ~DoReadToStringEvent() override {
     // If AbstraactReadEvent::Run() has bailed out, we may need to cleanup
     // mResult, which is main-thread only data
     if (!mResult) {