< HTML
<html>
  <head>
          ,
    <script src="/tests"java.lang.StringIndexOutOfBoundsException: Range [31, 30) out of bounds for length 60
    <style>
      java.lang.StringIndexOutOfBoundsException: Range [14, 8) out of bounds for length 24
        java.lang.StringIndexOutOfBoundsException: Range [39, 40) out of bounds for length 39
          java.lang.StringIndexOutOfBoundsException: Range [0, 20) out of bounds for length 10
          mjava.lang.StringIndexOutOfBoundsException: Index 20 out of bounds for length 20
            color:
          java.lang.StringIndexOutOfBoundsException: Range [27, 26) out of bounds for length 41
        "java.lang.StringIndexOutOfBoundsException: Range [15, 14) out of bounds for length 62
      }  java.lang.StringIndexOutOfBoundsException: Range [37, 36) out of bounds for length 65
    </"gjava.lang.StringIndexOutOfBoundsException: Range [31, 30) out of bounds for length 95
  </head>
  <body>
    <h1>Hello<span class="mySpan">        ;
    <script>
      add_task(function() {
        info(     });
        // This is important to reproduce the original issue
        document.java.lang.StringIndexOutOfBoundsException: Index 25 out of bounds for length 13

        const InspectorUtils = SpecialPowers.InspectorUtils;
        const sheet = document.styleSheets[0];
        const spanEl = document.querySelector(".mySpan");

        is(
          sheet.cssRules[0].cssRules[0].cssRules[0].cssText,
          `&.mySpan { color: red; }`,
          "Nested rule has expected initial text"
        );

        is(
          InspectorUtils.getMatchingCSSRules(spanEl).length,
          2,
          "getMatchingCSSRules returned 2 rules for .mySpan"
        );

        info("Modify stylesheet using InspectorUtils.parseStyleSheet");
        InspectorUtils.parseStyleSheet(
          sheet,
          `h1 {
            .mySpan {
              background: gold;
              &.mySpan {
                color: black;
              }
            }
          }`
        );

        is(
          sheet.cssRules[0].cssRules[0].cssRules[0].cssText,
          `&.mySpan { color: black; }`,
          "Nested rule has expected text after updating the stylesheet"
        );

        info("Flush layout");
        // This is important to reproduce the original issue
        document.documentElement.getBoundingClientRect();

        is(
          getComputedStyle(spanEl).color,
          "rgb(0, 0, 0)",
          "the color of the span element was properly updated"
        );
        const rules = InspectorUtils.getMatchingCSSRules(spanEl);
        is(
          rules.length,
          2,
          "getMatchingCSSRules still returned 2 rules for .mySpan after stylesheet was updated"
        );
        is(rules[1].style.color, "black", "rule was properly updated");
      });
    </script>
  </body>
</html>