add all frontend files

node_modules/rc-image/lib/util.js

@@ -0,0 +1,22 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.isImageValid = isImageValid;
+function isImageValid(src) {
+  return new Promise(function (resolve) {
+    if (!src) {
+      resolve(false);
+      return;
+    }
+    var img = document.createElement('img');
+    img.onerror = function () {
+      return resolve(false);
+    };
+    img.onload = function () {
+      return resolve(true);
+    };
+    img.src = src;
+  });
+}