diff -r 000000000000 -r 6474c204b198 layout/tools/reftest/reftest-preferences.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/layout/tools/reftest/reftest-preferences.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,48 @@
+    // For mochitests, we're more interested in testing the behavior of in-
+    // content XBL bindings, so we set this pref to true. In reftests, we're
+    // more interested in testing the behavior of XBL as it works in chrome,
+    // so we want this pref to be false.
+    branch.setBoolPref("dom.use_xbl_scopes_for_remote_xul", false);
+    branch.setBoolPref("gfx.color_management.force_srgb", true);
+    branch.setBoolPref("browser.dom.window.dump.enabled", true);
+    branch.setIntPref("ui.caretBlinkTime", -1);
+    branch.setBoolPref("dom.send_after_paint_to_content", true);
+    // no slow script dialogs
+    branch.setIntPref("dom.max_script_run_time", 0);
+    branch.setIntPref("dom.max_chrome_script_run_time", 0);
+    branch.setIntPref("hangmonitor.timeout", 0);
+    // Ensure autoplay is enabled for all platforms.
+    branch.setBoolPref("media.autoplay.enabled", true);
+    // Disable updates
+    branch.setBoolPref("app.update.enabled", false);
+    // Disable addon updates and prefetching so we don't leak them
+    branch.setBoolPref("extensions.update.enabled", false);
+    branch.setBoolPref("extensions.getAddons.cache.enabled", false);
+    // Disable blocklist updates so we don't have them reported as leaks
+    branch.setBoolPref("extensions.blocklist.enabled", false);
+    // Make url-classifier updates so rare that they won't affect tests
+    branch.setIntPref("urlclassifier.updateinterval", 172800);
+    // Disable high-quality downscaling, since it makes reftests more difficult.
+    branch.setBoolPref("image.high_quality_downscaling.enabled", false);
+    // Checking whether two files are the same is slow on Windows.
+    // Setting this pref makes tests run much faster there.
+    branch.setBoolPref("security.fileuri.strict_origin_policy", false);
+    // Disable the thumbnailing service
+    branch.setBoolPref("browser.pagethumbnails.capturing_disabled", true);
+    // Since our tests are 800px wide, set the assume-designed-for width of all
+    // pages to be 800px (instead of the default of 980px). This ensures that
+    // in our 800px window we don't zoom out by default to try to fit the
+    // assumed 980px content.
+    branch.setIntPref("browser.viewport.desktopWidth", 800);
+    // Disable the fade out (over time) of overlay scrollbars, since we
+    // can't guarantee taking both reftest snapshots at the same point
+    // during the fade.
+    branch.setBoolPref("layout.testing.overlay-scrollbars.always-visible", true);
+    // Disable interruptible reflow since (1) it's normally not going to
+    // happen, but (2) it might happen if we somehow end up with both
+    // pending user events and clock skew.  So to avoid having to change
+    // MakeProgress to deal with waiting for interruptible reflows to
+    // complete for a rare edge case, we just disable interruptible
+    // reflow so that that rare edge case doesn't lead to reftest
+    // failures.
+    branch.setBoolPref("layout.interruptible-reflow.enabled", false);