--- a/browser/components/extensions/ext-utils.js
+++ b/browser/components/extensions/ext-utils.js
@@ -528,17 +528,16 @@ class Tab extends TabBase {
    * @returns {Object}
    * @static
    */
   static convertFromSessionStoreClosedData(extension, tabData, window = null) {
     let result = {
       sessionId: String(tabData.closedId),
       index: tabData.pos ? tabData.pos : 0,
       windowId: window && windowTracker.getId(window),
-      selected: false,
       highlighted: false,
       active: false,
       pinned: false,
       incognito: Boolean(tabData.state && tabData.state.isPrivate),
     };
 
     if (extension.tabManager.hasTabPermission(tabData)) {
       let entries = tabData.state ? tabData.state.entries : tabData.entries;

--- a/browser/components/extensions/test/browser/browser_ext_sessions_getRecentlyClosed_tabs.js
+++ b/browser/components/extensions/test/browser/browser_ext_sessions_getRecentlyClosed_tabs.js
@@ -3,16 +3,19 @@
 "use strict";
 
 function expectedTabInfo(tab, window) {
   let browser = tab.linkedBrowser;
   return {
     url: browser.currentURI.spec,
     title: browser.contentTitle,
     favIconUrl: window.gBrowser.getIcon(tab),
+    // 'selected' is marked as unsupported in schema, so we've removed it.
+    // For more details, see bug 1337509
+    selected: undefined,
   };
 }
 
 function checkTabInfo(expected, actual) {
   for (let prop in expected) {
     is(actual[prop], expected[prop], `Expected value found for ${prop} of tab object.`);
   }
 }

--- a/browser/components/extensions/test/browser/browser_ext_tabs_create.js
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_create.js
@@ -36,16 +36,19 @@ add_task(function* test_create_options()
 
         function runTests() {
           const DEFAULTS = {
             index: 2,
             windowId: activeWindow,
             active: true,
             pinned: false,
             url: "about:newtab",
+            // 'selected' is marked as unsupported in schema, so we've removed it.
+            // For more details, see bug 1337509
+            selected: undefined,
           };
 
           let tests = [
             {
               create: {url: "http://example.com/"},
               result: {url: "http://example.com/"},
             },
             {

--- a/browser/components/extensions/test/browser/browser_ext_tabs_duplicate.js
+++ b/browser/components/extensions/test/browser/browser_ext_tabs_duplicate.js
@@ -17,18 +17,18 @@ add_task(function* testDuplicateTab() {
         let source = tabs[1];
         // By moving it 0, we check that the new tab is created next
         // to the existing one.
         browser.tabs.move(source.id, {index: 0}, () => {
           browser.tabs.duplicate(source.id, (tab) => {
             browser.test.assertEq("http://example.net/", tab.url);
             // Should be the second tab, next to the one duplicated.
             browser.test.assertEq(1, tab.index);
-            // Should be selected by default.
-            browser.test.assertTrue(tab.selected);
+            // Should be active by default.
+            browser.test.assertTrue(tab.active);
             browser.test.notifyPass("tabs.duplicate");
           });
         });
       });
     },
   });
 
   yield extension.startup();

--- a/browser/components/extensions/test/browser/head_sessions.js
+++ b/browser/components/extensions/test/browser/head_sessions.js
@@ -19,17 +19,17 @@ function checkWindow(window) {
     is(window[prop], false, `closed window has the expected value for ${prop}`);
   }
   for (let prop of ["state", "type"]) {
     is(window[prop], "normal", `closed window has the expected value for ${prop}`);
   }
 }
 
 function checkTab(tab, windowId, incognito) {
-  for (let prop of ["selected", "highlighted", "active", "pinned"]) {
+  for (let prop of ["highlighted", "active", "pinned"]) {
     is(tab[prop], false, `closed tab has the expected value for ${prop}`);
   }
   is(tab.windowId, windowId, "closed tab has the expected value for windowId");
   is(tab.incognito, incognito, "closed tab has the expected value for incognito");
 }
 
 function checkRecentlyClosed(recentlyClosed, expectedCount, windowId, incognito = false) {
   let sessionIds = new Set();

--- a/toolkit/components/extensions/ExtensionTabs.jsm
+++ b/toolkit/components/extensions/ExtensionTabs.jsm
@@ -456,17 +456,16 @@ class TabBase {
    *
    * @returns {object}
    */
   convert() {
     let result = {
       id: this.id,
       index: this.index,
       windowId: this.windowId,
-      selected: this.selected,
       highlighted: this.selected,
       active: this.selected,
       pinned: this.pinned,
       status: this.status,
       incognito: this.incognito,
       width: this.width,
       height: this.height,
       audible: this.audible,