add IE11 polyfill to support URI download scheme

packages/node_modules/@node-red/editor-client/src/js/polyfills.js

@@ -53,5 +53,31 @@
             Set.prototype.constructor = Set;
         }
 
+        if (window.navigator.msSaveBlob) {
+            // IE does not support data uri scheme for downloading data
+            window.addEventListener("click", function (ev) {
+                var tgt = ev.target;
+                if ((tgt.tagName === "A") &&
+                    tgt.hasAttribute("download") &&
+                    tgt.hasAttribute("href")) {
+                    // partial support of data uri downloading
+                    var filename = tgt.getAttribute("download");
+                    var dataUri = tgt.getAttribute("href");
+                    var match = /^data:([^,]+),(.*)/.exec(dataUri);
+                    if (match) {
+                        ev.preventDefault();
+                        var enc = match[1];
+                        var data = decodeURIComponent(match[2]);
+                        var blob = new Blob([data], {
+                            type: enc,
+                        });
+                        navigator.msSaveBlob(blob, filename);
+                    }
+                    else {
+                        console.log("download not supported:", tgt);
+                    }
+                }
+            });
+        }
     }
 })();