Platform: update {Emscripten,Sdl2}App cursor using Module['canvas'].

src/Magnum/Platform/EmscriptenApplication.cpp

@@ -703,7 +703,7 @@ void EmscriptenApplication::setCursor(Cursor cursor) {
     CORRADE_INTERNAL_ASSERT(UnsignedInt(cursor) < Containers::arraySize(CursorMap));
     #pragma GCC diagnostic push
     #pragma GCC diagnostic ignored "-Wdollar-in-identifier-extension"
-    EM_ASM_({document.getElementById('canvas').style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
+    EM_ASM_({Module['canvas'].style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
     #pragma GCC diagnostic pop
 }
 

src/Magnum/Platform/Sdl2Application.cpp

@@ -1072,7 +1072,7 @@ void Sdl2Application::setCursor(Cursor cursor) {
     CORRADE_INTERNAL_ASSERT(UnsignedInt(cursor) < Containers::arraySize(CursorMap));
     #pragma GCC diagnostic push
     #pragma GCC diagnostic ignored "-Wdollar-in-identifier-extension"
-    EM_ASM_({document.getElementById('canvas').style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
+    EM_ASM_({Module['canvas'].style.cursor = AsciiToString($0);}, CursorMap[UnsignedInt(cursor)]);
     #pragma GCC diagnostic pop
     #endif
 }