Bug 1714276 - Limit height of tab when font size is changed r=dao,desktop-theme-reviewers

Set a maximum height on tabs to prevent it from expanding and moving the display of the web page.

Differential Revision: https://phabricator.services.mozilla.com/D134169

browser/base/content/tabbrowser-tab.js

@@ -26,6 +26,7 @@
                 onoverflow="this.setAttribute('textoverflow', 'true');"
                 onunderflow="this.removeAttribute('textoverflow');"
                 align="start"
+                pack="center"
                 flex="1">
             <label class="tab-text tab-label" role="presentation"/>
             <hbox class="tab-secondary-label">

browser/themes/shared/tabs.inc.css

@@ -468,6 +468,10 @@
   display: none;
 }
 
+#tabbrowser-tabs:not([secondarytext-unsupported]) .tab-label-container {
+  height: 2.7em;
+}
+
 .tab-secondary-label {
   font-size: .75em;
   opacity: .8;