Remove IE11 support

With master now on 1.13, it's time to drop IE11 for good. The woff
variants are also in use by Opera Mini but it has even less market share
and I can only imagine how broken the UI is in it.

Fixes: #6147

package.json

@@ -58,6 +58,8 @@
     "updates": "10.2.11"
   },
   "browserslist": [
-    "defaults"
+    "defaults",
+    "not ie > 0",
+    "not ie_mob > 0"
   ]
 }

web_src/js/index.js

@@ -3,7 +3,6 @@
 /* exported toggleDeadlineForm, setDeadline, updateDeadline, deleteDependencyModal, cancelCodeComment, onOAuthLoginClick */
 
 import './publicpath.js';
-import './polyfills.js';
 
 import Vue from 'vue';
 import 'jquery.are-you-sure';

web_src/js/publicpath.js

@@ -1,11 +1,5 @@
 // This sets up webpack's chunk loading to load resources from the 'public'
 // directory. This file must be imported before any lazy-loading is being attempted.
 
-if (document.currentScript && document.currentScript.src) {
-  const url = new URL(document.currentScript.src);
-  __webpack_public_path__ = url.pathname.replace(/\/[^/]*?\/[^/]*?$/, '/');
-} else {
-  // compat: IE11
-  const script = document.querySelector('script[src*="/index.js"]');
-  __webpack_public_path__ = script.getAttribute('src').replace(/\/[^/]*?\/[^/]*?$/, '/');
-}
+const url = new URL(document.currentScript.src);
+__webpack_public_path__ = url.pathname.replace(/\/[^/]*?\/[^/]*?$/, '/');

web_src/less/_base.less

@@ -7,9 +7,7 @@
         local('Roboto'),
         local('Roboto-Regular'),
         /* Chrome 26+, Opera 23+, Firefox 39+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-regular.woff2') format('woff2'),
-        /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-regular.woff') format('woff');
+        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-regular.woff2') format('woff2');
 }
 
 /* roboto-italic - latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext */
@@ -20,10 +18,7 @@
     src:
         local('Roboto Italic'),
         local('Roboto-Italic'),
-        /* Chrome 26+, Opera 23+, Firefox 39+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-italic.woff2') format('woff2'),
-        /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-italic.woff') format('woff');
+        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-italic.woff2') format('woff2');
 }
 
 /* roboto-700 - latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext */
@@ -34,10 +29,7 @@
     src:
         local('Roboto Bold'),
         local('Roboto-Bold'),
-        /* Chrome 26+, Opera 23+, Firefox 39+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700.woff2') format('woff2'),
-        /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700.woff') format('woff');
+        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700.woff2') format('woff2');
 }
 
 /* roboto-700italic - latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext */
@@ -48,10 +40,7 @@
     src:
         local('Roboto Bold Italic'),
         local('Roboto-BoldItalic'),
-        /* Chrome 26+, Opera 23+, Firefox 39+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700italic.woff2') format('woff2'),
-        /* Chrome 6+, Firefox 3.6+, IE 9+, Safari 5.1+ */
-        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700italic.woff') format('woff');
+        url('../vendor/assets/roboto-fonts/roboto-v20-latin-ext_cyrillic-ext_latin_greek_vietnamese_cyrillic_greek-ext-700italic.woff2') format('woff2');
 }
 
 @font-face {