Bug 1550571 - Pref on Browsing Context preservation r=kmag,remote-protocol-reviewers,whimboo

Differential Revision: https://phabricator.services.mozilla.com/D77764

modules/libpref/init/StaticPrefList.yaml

@@ -3462,10 +3462,10 @@
 
 # This pref has no effect within fission windows, it only controls the
 # behaviour within non-fission windows. If true, preserve browsing contexts
-# between process swaps. Should be set to true in bug 1550571.
+# between process swaps.
 - name: fission.preserve_browsing_contexts
   type: bool
-  value: false
+  value: true
   mirror: always
 
 # Store the session history in the parent process, and access it over IPC

remote/test/browser/page/browser_navigate.js

@@ -234,7 +234,7 @@ add_task(async function testFileURL({ client }) {
   is(browser.currentURI.spec, url, "Expected URL loaded");
   const currentFrame = await getCurrentFrame();
   // Bug 1634695 Navigating to file: returns wrong frame id
-  todo(frameId === currentFrame.id, "Page.navigate returns expected frameId");
+  ok(frameId === currentFrame.id, "Page.navigate returns expected frameId");
 });
 
 add_task(async function testAbout({ client }) {