test(Angular): fix angularInit() tests on Safari v15+

Previously, the `angularInit()` tests assumed that the Safari browser
uses the `safari-extension:` protocol for browser extension URLs. This
is true for versions <15. However, since v15, Safari on iOS only
recognizes the `chrome-extension:` protocol, which causes the tests to
fail ([example failure][1]).

This commit updates the tests to use the correct protocol according to
the version of Safari used.

NOTE:
On macOS, Safari v15+ recognizes both `safari-extension:` and
`chrome-extension:`, so it is OK to always use the later with Safari
v15+ (regardless of the platform).

[1]: https://circleci.com/gh/angular/angular.js/3527

Co-authored-by: George Kalpakas <kalpakas.g@gmail.com>

Closes #17166

test/AngularSpec.js

@@ -1793,7 +1793,12 @@ describe('angular', function() {
           } else if (/Chrome\//.test(userAgent)) {
             protocol = 'chrome-extension:';
           } else if (/Safari\//.test(userAgent)) {
-            protocol = 'safari-extension:';
+            // On iOS, Safari versions <15 recognize `safari-extension:`, while versions >=15 only
+            // recognize `chrome-extension:`.
+            // (On macOS, Safari v15 recognizes both protocols, so it is fine to use either.)
+            var majorVersionMatch = /Version\/(\d+)/.exec(userAgent);
+            var majorVersion = majorVersionMatch ? parseInt(majorVersionMatch[1], 10) : 0;
+            protocol = (majorVersion < 15) ? 'safari-extension:' : 'chrome-extension:';
           } else {
             protocol = 'browserext:';  // Upcoming standard scheme.
           }