[emscripten] Remove reference to Module['createContext']

Backported from https://github.com/libsdl-org/SDL/pull/12970

(cherry picked from commit c0f78dee5efc2c5738e5cba52d8cdd84722ebe8e)

src/video/emscripten/SDL_emscriptenframebuffer.c

@@ -79,7 +79,7 @@ int Emscripten_UpdateWindowFramebuffer(_THIS, SDL_Window *window, const SDL_Rect
         if (!Module['SDL2']) Module['SDL2'] = {};
         var SDL2 = Module['SDL2'];
         if (SDL2.ctxCanvas !== Module['canvas']) {
-            SDL2.ctx = Module['createContext'](Module['canvas'], false, true);
+            SDL2.ctx = Browser.createContext(Module['canvas'], false, true);
             SDL2.ctxCanvas = Module['canvas'];
         }
         if (SDL2.w !== w || SDL2.h !== h || SDL2.imageCtx !== SDL2.ctx) {