1209603-1.html - mozsearch

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<!DOCTYPE HTML>

<title>Testcase, bug 1209603</title>

<style>

p {

  font-size: 2em;

  /* ensure font-size dependency in the margin struct; this is also in

     the UA style sheet, but repeated here for clarity */

  margin: 1em 0;

</style>

<div style="font-size: 20px"><p id="a">Should be 40px font size.</p></div>

<script>

var a = document.getElementById("a");

// force computation of the margin struct on A (caching in rule tree)

getComputedStyle(a, "").marginTop;

</script>

<!-- will dynamically change font-size to 10px later;

     also needs to be different from 20px now to avoid sibling-sharing -->

<div style="font-size: 30px"><p id="b">Should be 20px font size.</p></div>

<script>

// Note that A and B share rule nodes, and note that the margin struct

// has been conditionally (on font size) cached on their shared rule node.

var b = document.getElementById("b");

// force ComputedStyle construction and computation of the font struct on

// B's parent

getComputedStyle(b.parentNode, "").fontSize;

// force ComputedStyle construction (and computation of the color

// struct) on B, but not the margin struct or font struct

getComputedStyle(b, "").color;

// restyle B and flush

b.parentNode.style.fontSize = "10px";

getComputedStyle(b, "").marginTop;

// This flush will call CalcStyleDifference on B, which will find no

// cached font struct on the old context, but which will find a

// cached margin struct on the rule node.

</script>