test_rules_out_of_sheets.html

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https://bugzilla.mozilla.org/show_bug.cgi?id=634373

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<head>

  <title>Test for Bug 634373</title>

  <script src="/tests/SimpleTest/SimpleTest.js"></script>

  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>

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<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=634373">Mozilla Bug 634373</a>

<p id="display"></p>

<div id="content" style="display: none">

</div>

<pre id="test">

<script type="application/javascript">

/** Test for Bug 634373 **/

function make_rule_and_remove_sheet(text, getter) {

  var style = document.createElement("style");

  style.setAttribute("type", "text/css");

  style.appendChild(document.createTextNode(text));

  document.head.appendChild(style);

  var result = style.sheet.cssRules[0];

  if (getter) {

    result = getter(result);

  document.head.removeChild(style);

  style = null;

  SpecialPowers.DOMWindowUtils.garbageCollect();

  return result;

var gDisplayCS = getComputedStyle(document.getElementById("display"), "");

function keep_rule_alive_by_matching(rule) {

  // It's the caller's job to guarantee that the rule matches a p.

  // This just causes a style flush, which in turn keeps the rule alive

  // until the next style flush.

  var color = gDisplayCS.color;

  return rule;

function get_rule_and_child(rule) {

  return [rule, rule.cssRules[0]];

function get_only_child(rule) {

  return rule.cssRules[0];

var rule;

// In this case, the rule goes away immediately, so we're testing

// the DOM wrapper's handling of a null rule, rather than the rule's

// handling of a null sheet.

rule = make_rule_and_remove_sheet("p { color: blue }");

rule.style.color = "";

try {

  rule.style.color = "fuchsia";

} catch(ex) {}

rule = make_rule_and_remove_sheet("p { color: blue }",

                                  keep_rule_alive_by_matching);

try {

  rule.style.color = "";

} catch(ex) {}

try {

  rule.style.color = "fuchsia";

} catch(ex) {}

rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",

                                   get_rule_and_child);

rule[1].style.color = "";

try {

  rule[1].style.color = "fuchsia";

} catch(ex) {}

// In this case, the rule goes away immediately, so we're testing

// the DOM wrapper's handling of a null rule, rather than the rule's

// handling of a null sheet.

rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",

                                   get_only_child);

rule.style.color = "";

try {

  rule.style.color = "fuchsia";

} catch(ex) {}

rule = make_rule_and_remove_sheet("@media screen { p { color: blue } }",

                                  function(ruleInner) {

                                    return keep_rule_alive_by_matching(

                                             get_only_child(ruleInner));

});

try {

  rule.style.color = "";

} catch(ex) {}

try {

  rule.style.color = "fuchsia";

} catch(ex) {}

rule = make_rule_and_remove_sheet("@keyframes a { from { color: blue } }");

rule.appendRule("from { color: fuchsia}");

rule.deleteRule("from");

rule.name = "b";

rule.cssRules[0].keyText = "50%";

ok(true, "didn't crash");

</script>

</pre>

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