Use override in more classes in fpdfsdk/

fpdfsdk/include/javascript/JS_Runtime.h

Index: fpdfsdk/include/javascript/JS_Runtime.h
diff --git a/fpdfsdk/include/javascript/JS_Runtime.h b/fpdfsdk/include/javascript/JS_Runtime.h
index 3be0f76549df80a7902eb0962cd0d96dc09884c6..1d40a645095292b12c9d6fe63f10324928734e56 100644
--- a/fpdfsdk/include/javascript/JS_Runtime.h
+++ b/fpdfsdk/include/javascript/JS_Runtime.h
@@ -31,14 +31,14 @@ class CJS_FieldEvent {
 class CJS_Runtime : public IFXJS_Runtime {
  public:
   CJS_Runtime(CPDFDoc_Environment* pApp);
-  virtual ~CJS_Runtime();
-
-  virtual IFXJS_Context* NewContext();
-  virtual void ReleaseContext(IFXJS_Context* pContext);
-  virtual IFXJS_Context* GetCurrentContext();
-
-  virtual void SetReaderDocument(CPDFSDK_Document* pReaderDoc);
-  virtual CPDFSDK_Document* GetReaderDocument() { return m_pDocument; }
+  ~CJS_Runtime() override;
+
+  // IFXJS_Runtime
+  IFXJS_Context* NewContext() override;
+  void ReleaseContext(IFXJS_Context* pContext) override;
+  IFXJS_Context* GetCurrentContext() override;
+  void SetReaderDocument(CPDFSDK_Document* pReaderDoc) override;
+  CPDFSDK_Document* GetReaderDocument() override { return m_pDocument; }
 
   CPDFDoc_Environment* GetReaderApp() { return m_pApp; }