Merge to XFA: Use override in more classes in fpdfsdk/

R=tsepez@chromium.org

Review URL: https://codereview.chromium.org/1287193005 .

(cherry picked from commit 0f6b51c0fdd14f5762bf3c7412ac59c825443cc3)

Review URL: https://codereview.chromium.org/1288393004 .
diff --git a/fpdfsdk/src/javascript/JS_Context.cpp b/fpdfsdk/src/javascript/JS_Context.cpp
index 9c142e6..b51b5aa 100644
--- a/fpdfsdk/src/javascript/JS_Context.cpp
+++ b/fpdfsdk/src/javascript/JS_Context.cpp
@@ -19,7 +19,7 @@
   m_pEventHandler = new CJS_EventHandler(this);
 }
 
-CJS_Context::~CJS_Context(void) {
+CJS_Context::~CJS_Context() {
   delete m_pEventHandler;
 }