[FIX] IE11 baseURI (#15319)

app/ui/client/components/icon.js

 import { FlowRouter } from 'meteor/kadira:flow-router';
 import { Template } from 'meteor/templating';
 
+import { baseURI } from '../../../utils/client/lib/baseuri';
+
 import './icon.html';
 
 
-const baseUrlFix = () => `${ document.baseURI }${ FlowRouter.current().path.substring(1) }`;
+const baseUrlFix = () => `${ baseURI }${ FlowRouter.current().path.substring(1) }`;
 
 const isMozillaFirefoxBelowVersion = (upperVersion) => {
 	const [, version] = navigator.userAgent.match(/Firefox\/(\d+)\.\d/) || [];

app/utils/client/lib/RestApiClient.js

 import { Meteor } from 'meteor/meteor';
 import { Accounts } from 'meteor/accounts-base';
 
+import { baseURI } from './baseuri';
+
 export const APIClient = {
 	delete(endpoint, params) {
 		return APIClient._jqueryCall('DELETE', endpoint, params);
@@ -47,7 +49,7 @@ export const APIClient = {
 		return new Promise(function _rlRestApiGet(resolve, reject) {
 			jQuery.ajax({
 				method,
-				url: `${ document.baseURI }api/${ endpoint }${ query }`,
+				url: `${ baseURI }api/${ endpoint }${ query }`,
 				headers: {
 					'Content-Type': 'application/json',
 					'X-User-Id': Meteor._localStorage.getItem(Accounts.USER_ID_KEY),
@@ -75,7 +77,7 @@ export const APIClient = {
 
 		return new Promise(function _jqueryFormDataPromise(resolve, reject) {
 			jQuery.ajax({
-				url: `${ document.baseURI }api/${ endpoint }${ query }`,
+				url: `${ baseURI }api/${ endpoint }${ query }`,
 				headers: {
 					'X-User-Id': Meteor._localStorage.getItem(Accounts.USER_ID_KEY),
 					'X-Auth-Token': Meteor._localStorage.getItem(Accounts.LOGIN_TOKEN_KEY),

app/utils/client/lib/baseuri.js

+export const baseURI = (() => {
+	if (document.baseURI) { return document.baseURI; }
+
+	// Should be exactly one tag:
+	//   https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base
+	const base = document.getElementsByTagName('base');
+
+	// Return location from BASE tag.
+	if (base.length > 0) { return base[0].href; }
+
+	// Else use implementation of documentURI:
+	//   http://www.w3.org/TR/DOM-Level-3-Core/core.html#Node3-baseURI
+	return document.URL;
+})();