Bug 1513200 - Move pre-tabs and post-tabs spacers outside of TabsToolbar-customization-target and revert bug 1445728. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D14142

--HG--
extra : moz-landing-system : lando

browser/base/content/browser.xul

@@ -762,13 +762,13 @@ xmlns="http://www.w3.org/1999/xhtml"
                aria-label="&tabsToolbar.label;"
                context="toolbar-context-menu"
                flex="1">
+
+        <hbox class="titlebar-spacer" type="pre-tabs"/>
+
         <vbox flex="1" class="toolbar-items">
           <spacer flex="1000"/>
 
           <hbox id="TabsToolbar-customization-target" flex="1">
-            <hbox class="titlebar-spacer" type="pre-tabs"
-                  skipintoolbarset="true"/>
-
             <tabs id="tabbrowser-tabs"
                   flex="1"
                   setfocus="false"
@@ -796,19 +796,15 @@ xmlns="http://www.w3.org/1999/xhtml"
                            label="&listAllTabs.label;"
                            tooltiptext="&listAllTabs.label;"
                            removable="false"/>
-
-            <hbox class="titlebar-spacer" type="post-tabs"
-                  ordinal="1000"
-                  skipintoolbarset="true"/>
           </hbox>
         </vbox>
 
+        <hbox class="titlebar-spacer" type="post-tabs"/>
+
 #ifndef XP_MACOSX
         <button class="accessibility-indicator" tooltiptext="&accessibilityIndicator.tooltip;"
-                ordinal="1000"
-                aria-live="polite" skipintoolbarset="true"/>
-        <hbox class="private-browsing-indicator" skipintoolbarset="true"
-              ordinal="1000"/>
+                aria-live="polite"/>
+        <hbox class="private-browsing-indicator"/>
 #endif
 
 #include titlebar-items.inc.xul

browser/base/content/tabbrowser.xml

@@ -1127,7 +1127,6 @@
 
           // Starting from the tabs element, find the next sibling that:
           // - isn't hidden; and
-          // - isn't one of the titlebar placeholder elements; and
           // - isn't the all-tabs button.
           // If it's the new tab button, consider the new tab button adjacent to the tabs.
           // If the new tab button is marked as adjacent and the tabstrip doesn't
@@ -1138,7 +1137,6 @@
           do {
             sib = unwrap(wrap(sib).nextElementSibling);
           } while (sib && (sib.hidden ||
-                           sib.getAttribute("skipintoolbarset") == "true" ||
                            sib.id == "alltabs-button"));
 
           const kAttr = "hasadjacentnewtabbutton";