Mark destructors of Surface and Context as virtual.

src/libEGL/Surface.h

@@ -37,7 +37,7 @@ class Surface
     Surface(Display *display, const egl::Config *config, HWND window, EGLint postSubBufferSupported);
     Surface(Display *display, const egl::Config *config, HANDLE shareHandle, EGLint width, EGLint height, EGLenum textureFormat, EGLenum textureTarget);
 
-    ~Surface();
+    virtual ~Surface();
 
     bool initialize();
     void release();

src/libGLESv2/Context.h

@@ -132,7 +132,7 @@ class Context
   public:
     Context(int clientVersion, const gl::Context *shareContext, rx::Renderer *renderer, bool notifyResets, bool robustAccess);
 
-    ~Context();
+    virtual ~Context();
 
     void makeCurrent(egl::Surface *surface);