Created Unassigned: having the text '' in javascript breaks generated code [130]

In MVC 5 Razor 3, (also upgraded to c#4.5.1)
having the following javascript breaks the generator.

<script>window.tinyMCE || document.write('<script src="//tinymce.cachefly.net/4.0/tinymce.min.js">\x3C/script>')</script>

it is having a '<script ' in text that is causing the issue
causes the error:
Custom tool error: The "script" element was not closed. All elements must be either self-closing or have a matching end tag.

if you change the javascript to:

<script>window.tinyMCE || document.write('\x3Cscript src="//tinymce.cachefly.net/4.0/tinymce.min.js">\x3C/script>')</script>

then it works fine.
But this worked for the previous version of MVC5 and Razor 3 without having to do this.