Fixed AMP test for 'static pages'

no issue

- 'static pages' (post of a page type) were not supported in v0.1 API
- this is where the 404 is comming from  - df7e64fafa/core/frontend/apps/amp/lib/router.js (L66). and it was handled in rather late stage before - df7e64fafa/core/frontend/apps/amp/lib/router.js (L24)
- after moveing to v2 API the later stage doesn't happen so the entry lookup helper doesn't have anough infomration to tell if it's a 'Post' or 'Page' is being requested

core/test/regression/site/frontend_spec.js

@@ -359,10 +359,12 @@ describe('Frontend Routing', function () {
 
             describe('amp', function () {
                 it('should 404 for amp parameter', function (done) {
+                    // NOTE: only post pages are supported so the router doesn't have a way to distinguish if
+                    //       the request was done after AMP 'Page' or 'Post'
                     request.get('/static-page-test/amp/')
                         .expect('Cache-Control', testUtils.cacheRules.private)
                         .expect(404)
-                        .expect(/Page not found/)
+                        .expect(/Post not found/)
                         .end(doEnd(done));
                 });
             });