WIP add heif_items API to emscripten

Author: dukesook

libheif/api/libheif/heif_emscripten.h

@@ -12,6 +12,7 @@
 #include <cassert>
 
 #include "heif.h"
+#include "heif_items.h"
 
 static std::string _heif_get_version()
 {
@@ -314,6 +315,7 @@ EMSCRIPTEN_BINDINGS(libheif) {
     EXPORT_HEIF_FUNCTION(heif_image_handle_get_height);
     EXPORT_HEIF_FUNCTION(heif_image_handle_is_primary_image);
     EXPORT_HEIF_FUNCTION(heif_image_release);
+    EXPORT_HEIF_FUNCTION(heif_context_get_number_of_items);
 
     emscripten::enum_<heif_error_code>("heif_error_code")
     .value("heif_error_Ok", heif_error_Ok)