fix: Syntax error in IE11 (codesandbox#1617)

Author: eps1lon

packages/app/src/app/index.html

@@ -59,9 +59,11 @@
           env: {
             VSCODE_DEV: false
           },
-          nextTick: (cb) => requestAnimationFrame(cb),
+          nextTick: function(cb) {
+            return requestAnimationFrame(cb);
+          },
           once: BrowserFS.BFSRequire('process').once,
-          removeListener: () => {}
+          removeListener: function () {}
         };
         window.Buffer = BrowserFS.BFSRequire('buffer').Buffer;
       }

packages/app/src/embed/index.html

@@ -48,9 +48,11 @@
           env: {
             VSCODE_DEV: false
           },
-          nextTick: (cb) => requestAnimationFrame(cb),
+          nextTick: function(cb) {
+            return requestAnimationFrame(cb);
+          },
           once: BrowserFS.BFSRequire('process').once,
-          removeListener: () => {}
+          removeListener: function () {}
         };
         window.Buffer = BrowserFS.BFSRequire('buffer').Buffer;
       }