Emscripten: remove GLES_DeleteContext implementation

It was calling glClear without a context. The issue it was trying to
solve was actually that after destroying a window and creating a new one
, the contents of the old window were preserved. This no longer happens
since we resize the window to nothing on destroy.

src/video/emscripten/SDL_emscriptenopengles.c

@@ -81,19 +81,6 @@ Emscripten_GLES_LoadLibrary(_THIS, const char *path) {
     return 0;
 }
 
-void
-Emscripten_GLES_DeleteContext(_THIS, SDL_GLContext context)
-{
-    /*
-    WebGL contexts can't actually be deleted, so we need to reset it.
-    ES2 renderer resets state on init anyway, clearing the canvas should be enough
-    */
-
-    glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
-
-    SDL_EGL_DeleteContext(_this, context);
-}
-
 SDL_EGL_CreateContext_impl(Emscripten)
 SDL_EGL_SwapWindow_impl(Emscripten)
 SDL_EGL_MakeCurrent_impl(Emscripten)

src/video/emscripten/SDL_emscriptenopengles.h

@@ -34,9 +34,9 @@
 #define Emscripten_GLES_UnloadLibrary SDL_EGL_UnloadLibrary
 #define Emscripten_GLES_SetSwapInterval SDL_EGL_SetSwapInterval
 #define Emscripten_GLES_GetSwapInterval SDL_EGL_GetSwapInterval
+#define Emscripten_GLES_DeleteContext SDL_EGL_DeleteContext
 
 extern int Emscripten_GLES_LoadLibrary(_THIS, const char *path);
-extern void Emscripten_GLES_DeleteContext(_THIS, SDL_GLContext context);
 extern SDL_GLContext Emscripten_GLES_CreateContext(_THIS, SDL_Window * window);
 extern int Emscripten_GLES_SwapWindow(_THIS, SDL_Window * window);
 extern int Emscripten_GLES_MakeCurrent(_THIS, SDL_Window * window, SDL_GLContext context);