Bug 1810141 - fix loadURI callers that already have an nsIURI reference or where creating one is clearly safe, r=mossop,geckoview-reviewers,extension-reviewers,settings-reviewers,mconley,m_kato

There are 3 types of changes in this commit:

- from `loadURI(foo.spec)` to `loadURI(foo)`, as there's already a URI
- from `loadURI("string")` to `loadURI(Services.io.newURI("string"))` as the URL is hardcoded
- one or two where there is perhaps an intermediate variable but the patch
  context should still make it trivial to ascertain the change is correct.

Depends on D168393

Differential Revision: https://phabricator.services.mozilla.com/D168394

browser/components/shell/HeadlessShell.jsm

@@ -58,7 +58,7 @@ function loadContentWindow(browser, url) {
         oa
       ),
     };
-    browser.loadURI(uri.spec, loadURIOptions);
+    browser.loadURI(uri, loadURIOptions);
     let { webProgress } = browser;
 
     let progressListener = {