Bug 1534399 - Don't allow disabling non-author sheets. r=emilio

Differential Revision: https://phabricator.services.mozilla.com/D23624 --HG-- extra : moz-landing-system : lando
2019-03-15 12:54:17 +00:00 · 2019-03-15 12:54:17 +00:00 · 716d720e13
--- a/layout/inspector/tests/chrome/chrome.ini
+++ b/layout/inspector/tests/chrome/chrome.ini
@ -29,3 +29,4 @@ skip-if = ((os == 'win' && bits!=64) || (os=='linux' && bits==32) || os == 'mac'
 support-files =
  test_fontVariationsAPI.css
 [test_fontFaceGeneric.xul]
+[test_ua_sheet_disable.html]
--- a/layout/inspector/tests/chrome/test_ua_sheet_disable.html
+++ b/layout/inspector/tests/chrome/test_ua_sheet_disable.html
@ -0,0 +1,20 @@
+<!DOCTYPE html>
+<title>Test for bug 1534399</title>
+<script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+<link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+<script>
+function start() {
+  let sheet = InspectorUtils.getAllStyleSheets(document, false)[0];
+  ok(sheet.href.indexOf("test.css") == -1, "Shouldn't have found the author sheet");
+
+  is(sheet.disabled, false, "Sheet should initially be enabled");
+
+  sheet.disabled = true;
+  is(sheet.disabled, false, "Shouldn't be able to disable a UA sheet");
+
+  SimpleTest.finish();
+}
+
+SimpleTest.waitForExplicitFinish();
+document.addEventListener('DOMContentLoaded', start)
+</script>
--- a/layout/style/StyleSheet.cpp
+++ b/layout/style/StyleSheet.cpp
@ -241,6 +241,11 @@ void StyleSheet::ApplicableStateChanged(bool aApplicable) {
 }

 void StyleSheet::SetDisabled(bool aDisabled) {
+  // Only allow disabling author sheets.
+  if (mParsingMode != css::eAuthorSheetFeatures) {
+    return;
+  }
+
  if (aDisabled == Disabled()) {
    return;
  }