title: CSSStyleDeclaration.getPropertyValue("background-image") returns diferente in Chrome and Firefox
body: <p>While I am working with CSSStyleSheet I need to retrieve a image URL.</p>
  
  <p>The following command: <code>style.getPropertyCSSValue("background-image")</code> (where <em>style</em> is a <em>CSSStyleDeclaration</em>) returns <code>url("../../assets-common/images/planeta.png")</code> in Firefox, but returns 
  <code>url(http://localhost:8080/assets-common/images/planeta.png)</code> in Chrome</p>
  
  <p>In the real CSS file the path is a relative one. (as in Firefox)</p>
  
  <p>Is there a framework or tool or script to make both explorers behave alike?</p>
  
  <p><strong>NOTE:</strong> I am accessing the CSSStyleDeclaration directly through CSSStyleSheet, I do not have a dom element to use getComputedStyle</p>