1 files changed, 35 insertions, 0 deletions
diff --git a/layout/style/test/test_shared_sheet_caching.html b/layout/style/test/test_shared_sheet_caching.html
new file mode 100644
index 0000000000..e59c0c139e
--- /dev/null
+++ b/layout/style/test/test_shared_sheet_caching.html
@@ -0,0 +1,35 @@
+<!doctype html>
+<meta charset="utf-8">
+<script src="/tests/SimpleTest/SimpleTest.js"></script>
+<script>
+  function childWindowLoaded(childWin) {
+    is(
+      childWin.getComputedStyle(childWin.document.documentElement).backgroundColor,
+      "rgb(0, 255, 0)",
+      "Sheet should apply",
+    )
+    is(
+      SpecialPowers.getDOMWindowUtils(childWin).parsedStyleSheets,
+      0,
+      `Shouldn't need to parse the stylesheet ${childWin.parent == window ? "frame" : "top"}`
+    );
+    if (childWin.top == childWin) {
+      SimpleTest.finish();
+    }
+  }
+</script>
+<link rel="stylesheet" href="file_shared_sheet_caching.css">
+<iframe src="file_shared_sheet_caching.html"></iframe>
+<a rel="opener" href="file_shared_sheet_caching.html" target="_blank">Navigation</a>
+<script>
+SimpleTest.waitForExplicitFinish();
+onload = function() {
+  info("Sheets parsed: " + SpecialPowers.DOMWindowUtils.parsedStyleSheets);
+  is(
+    getComputedStyle(document.documentElement).backgroundColor,
+    "rgb(0, 255, 0)",
+    "Sheet should apply",
+  )
+  document.querySelector("a").click();
+}
+</script>