add web sync files and key events

webgl/src/mylib.js

@@ -1,3 +1,13 @@
+function js_sync() {
+  if (Module.js_fs_synching)
+    return;
+  Module.js_fs_synching = true;
+  FS.syncfs(function (err) {
+    console.log("syncFS result:");
+    console.log(err);
+    Module.js_fs_synching = false;
+  });
+}
 function js_pick_file(fn) {
     var input = document.createElement('input');
     input.type = 'file';
@@ -55,6 +65,7 @@ function js_pick_file_save(path, name, fn) {
 }
 
 mergeInto(LibraryManager.library, {
+  js_sync: js_sync,
   js_pick_file: js_pick_file,
   js_pick_file_save: js_pick_file_save,
 });