Fix Internet Explorer

Looks like this got merged before it got tested, and broke IE.  Apparently
we still have users using it, as they noticed pretty quick.  we might
want to keep that in mind for the future.

A short note on the failure, this snippet contained a section that
enabled use scrict on the code, which accidentally allowed babel to
enable it everywhere.  So far as I can tell, the existing code doesn't
follow strict (although there's only one outlier).

in short, this fixes IE.

Tested:
Launched webui in IE11 with debug console open.  Observed UI launches
with no unexpected warnings.

Signed-off-by: Ed Tanous <ed@tanous.net>
Change-Id: I85cc83b34f4f5906e827ea55c4b4fb4bda0fe6ac
diff --git a/app/common/directives/serial-console.js b/app/common/directives/serial-console.js
index 59ffe78..8d322f1 100644
--- a/app/common/directives/serial-console.js
+++ b/app/common/directives/serial-console.js
@@ -39,9 +39,8 @@
 // that anymore? Grabbed from
 // https://developer.mozilla.org/en-US/docs/Web/API/TextEncoder#Polyfill
 if (typeof TextEncoder === 'undefined') {
-  TextEncoder = function TextEncoder() {};
+  let TextEncoder = function TextEncoder() {};
   TextEncoder.prototype.encode = function encode(str) {
-    'use strict';
     var Len = str.length, resPos = -1;
     // The Uint8Array's length must be at least 3x the length of the string
     // because an invalid UTF-16