Bug 583000 - Don't try to measure the tab width if there is only one tab. Fixes broken popup windows with browser.tabs.closeWindowWithLastTab=false where accessing tabbrowser.tabs during the construction of tabbrowser-tabs would fail. r=gavin

--HG--
extra : rebase_source : 2fd228cf6903d910ff352f8f754ab1334924c08d

browser/base/content/tabbrowser.xml

@@ -2650,9 +2650,12 @@
               this.setAttribute("closebuttons", "activetab");
             break;
           case 1:
-            if (this.childNodes.length == 1 && this._closeWindowWithLastTab)
-              this.setAttribute("closebuttons", "noclose");
-            else {
+            if (this.childNodes.length == 1) {
+              if (this._closeWindowWithLastTab)
+                this.setAttribute("closebuttons", "noclose");
+              else
+                this.setAttribute("closebuttons", "alltabs");
+            } else {
               let tab = this.tabbrowser.visibleTabs[this.tabbrowser._numPinnedTabs];
               if (tab && tab.getBoundingClientRect().width > this.mTabClipWidth)
                 this.setAttribute("closebuttons", "alltabs");