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<!doctype html>
<meta charset="utf-8">
<title>
  Test for bug 1519371: We don't reframe for changes that affect our containing
  block status unless whether we're a containing block really changed.
</title>
<link rel="author" href="mailto:emilio@crisal.io" title="Emilio Cobos Álvarez">
<script src="/tests/SimpleTest/SimpleTest.js"></script>
<div id="content"></div>
<script>
SimpleTest.waitForExplicitFinish();
const utils = SpecialPowers.getDOMWindowUtils(window);

function expectReframe(shouldHaveReframed, callback) {
  document.documentElement.offsetTop;
  const previousConstructCount = utils.framesConstructed;
  const previousRestyleGeneration = utils.restyleGeneration;

  callback();

  document.documentElement.offsetTop;
  isnot(previousRestyleGeneration, utils.restyleGeneration,
        "We should have restyled");
  (shouldHaveReframed ? isnot : is)(previousConstructCount,
                                    utils.framesConstructed,
    `We should ${shouldHaveReframed ? "" : "not"} have reframed`);
}

const content = document.getElementById("content");

// Without fixed-pos descendants, we should not reframe.
expectReframe(false, () => {
  content.style.transform = "scale(1)";
});

content.style.transform = "";
content.innerHTML = `<div style="position: fixed"></div>`;

// With fixed-pos descendants, got to reframe.
expectReframe(true, () => {
  content.style.transform = "scale(1)";
});

// If our containing-block-ness didn't change, we should not need to reframe.
expectReframe(false, () => {
  content.style.willChange = "transform";
});

// If it does change, we need to reframe.
expectReframe(true, () => {
  content.style.willChange = "";
  content.style.transform = "";
});

SimpleTest.finish();
</script>