Full page image: fix scrolling with the new native scroll (#524)

* fix scroll div selector

* add test

* increase timeout

* fix test image

* use ID instead of class

* revert to class

* use both ID and class

Author: AgnesToulet

jest.config.js

@@ -3,4 +3,5 @@ module.exports = {
   preset: 'ts-jest',
   testEnvironment: 'node',
   reporters: ['<rootDir>/tests/reporter.js'],
+  testTimeout: 20000,
 };