Bug 1845895 - Allow profile manager richlistbox to shrink. r=Gijs

Differential Revision: https://phabricator.services.mozilla.com/D184818

toolkit/profile/content/profileSelection.xhtml

@@ -54,7 +54,7 @@
 
     <separator class="thin" />
 
-    <hbox class="profile-box indent" flex="1">
+    <hbox class="indent">
       <vbox id="managebuttons">
         <button
           id="newbutton"
@@ -73,7 +73,7 @@
         />
       </vbox>
 
-      <vbox flex="1">
+      <vbox id="profilesContainer">
         <richlistbox
           id="profiles"
           class="theme-listbox"

toolkit/themes/shared/profileSelection.css

@@ -8,6 +8,11 @@
   padding-top: 1em;
 }
 
+#profilesContainer {
+  flex: 1;
+  min-width: 0;
+}
+
 #profiles {
   height: 12em;
 }