--- a/browser/base/content/browser.css
+++ b/browser/base/content/browser.css
@@ -448,17 +448,17 @@ toolbar:not(#TabsToolbar) > #personal-bo
 }
 
 #zoom-controls[cui-areatype="toolbar"]:not([overflowedItem=true]) > #zoom-reset-button > .toolbarbutton-text {
   display: -moz-box;
 }
 
 #reload-button:not([displaystop]) + #stop-button,
 #reload-button[displaystop] {
-  visibility: collapse;
+  display: none;
 }
 
 /* The reload-button is only disabled temporarily when it becomes visible
    to prevent users from accidentally clicking it. We don't however need
    to show this disabled state, as the flicker that it generates is short
    enough to be visible but not long enough to explain anything to users. */
 #reload-button[disabled]:not(:-moz-window-inactive) > .toolbarbutton-icon {
   opacity: 1 !important;
@@ -670,17 +670,17 @@ html|input.urlbar-input[textoverflow]:no
 #urlbar[pageproxystate=invalid] > #page-action-buttons > .urlbar-page-action,
 #identity-box.chromeUI ~ #page-action-buttons > .urlbar-page-action,
 #urlbar[usertyping] > .urlbar-textbox-container > .urlbar-history-dropmarker,
 .urlbar-go-button[pageproxystate="valid"],
 .urlbar-go-button:not([parentfocused="true"]),
 #urlbar[pageproxystate="invalid"] > #identity-box > #blocked-permissions-container,
 #urlbar[pageproxystate="invalid"] > #identity-box > #notification-popup-box,
 #urlbar[pageproxystate="invalid"] > #identity-box > #identity-icon-labels {
-  visibility: collapse;
+  display: none;
 }
 
 #identity-box {
   -moz-user-focus: normal;
 }
 
 #urlbar[pageproxystate="invalid"] > #identity-box {
   pointer-events: none;

--- a/browser/base/content/test/performance/browser_startup_images.js
+++ b/browser/base/content/test/performance/browser_startup_images.js
@@ -12,42 +12,20 @@
  *  - platforms: An array of the platforms where the issue is occurring.
  *               Possible values are linux, win, macosx.
  *  - intermittentNotLoaded: an array of platforms where this image is
  *                           intermittently not loaded, e.g. because it is
  *                           loaded during the time we stop recording.
  *  - intermittentShown: An array of platforms where this image is
  *                       intermittently shown, contrary to what our
  *                       whitelist says.
- *  - photon: If true, this entry only applies for builds with the Photon theme.
- *            If false, this entry only applies for builds without the Photon theme.
- *            If undefined, this entry applies for both Photon and non-Photon builds.
  *
  * Please don't add items to this list. Please remove items from this list.
  */
 const whitelist = [
-  // Photon-only entries
-  {
-    file: "chrome://browser/skin/stop.svg",
-    platforms: ["linux", "win", "macosx"],
-  },
-  {
-    file: "chrome://browser/skin/bookmark-hollow.svg",
-    platforms: ["linux", "win", "macosx"],
-  },
-  {
-    file: "chrome://browser/skin/page-action.svg",
-    platforms: ["linux", "win", "macosx"],
-  },
-  {
-    file: "chrome://pocket-shared/skin/pocket.svg",
-    platforms: ["linux", "win", "macosx"],
-  },
-
-  // Shared entries
   {
     file: "chrome://browser/skin/arrow-left.svg",
     platforms: ["linux", "win", "macosx"],
   },
   {
     file: "chrome://browser/skin/tabbrowser/tab-overflow-indicator.png",
     platforms: ["linux", "win", "macosx"],
   },

--- a/browser/base/content/test/urlbar/browser_page_action_menu.js
+++ b/browser/base/content/test/urlbar/browser_page_action_menu.js
@@ -118,32 +118,32 @@ add_task(async function sendToDevice_non
   // Open a tab that's not sendable.  An about: page like about:home is
   // convenient.
   await BrowserTestUtils.withNewTab("about:home", async () => {
     // ... but the page actions should be hidden on about:home, including the
     // main button.  (It's not easy to load a page that's both actionable and
     // not sendable.)  So first check that that's the case, and then unhide the
     // main button so that this test can continue.
     Assert.equal(
-      window.getComputedStyle(BrowserPageActions.mainButtonNode).visibility,
-      "collapse",
+      window.getComputedStyle(BrowserPageActions.mainButtonNode).display,
+      "none",
       "Main button should be hidden on about:home"
     );
-    BrowserPageActions.mainButtonNode.style.visibility = "visible";
+    BrowserPageActions.mainButtonNode.style.display = "-moz-box";
     await promiseSyncReady();
     // Open the panel.  Send to Device should be disabled.
     await promisePageActionPanelOpen();
     let sendToDeviceButton =
       document.getElementById("pageAction-panel-sendToDevice");
     Assert.ok(sendToDeviceButton.disabled);
     let hiddenPromise = promisePageActionPanelHidden();
     BrowserPageActions.panelNode.hidePopup();
     await hiddenPromise;
-    // Remove the `visibility` style set above.
-    BrowserPageActions.mainButtonNode.style.removeProperty("visibility");
+    // Remove the `display` style set above.
+    BrowserPageActions.mainButtonNode.style.removeProperty("display");
   });
 });
 
 add_task(async function sendToDevice_syncNotReady_other_states() {
   // Open a tab that's sendable.
   await BrowserTestUtils.withNewTab("http://example.com/", async () => {
     await promiseSyncReady();
     const sandbox = sinon.sandbox.create();