title: LESS escaping not working
body: <p>I'm using Gulp (w/ Gulp-LESS) to compile LESS to CSS. For some reason, it's not recognizing when I try to escape a CSS calculation.</p>
  
  <p>Both of these:</p>
  
  <pre><code>height: ~"calc(100vh - 50px)";
  height: calc(~"100vh - 50px");
  </code></pre>
  
  <p>Always compiles to this:</p>
  
  <pre><code>height: calc(50vh);
  </code></pre>
  
  <p>I know there's a way to turn on Strict Math in LESS, but I'm not sure how to do that within the Gulp workflow.</p>