Issue #2389455 by hussainweb, AjitS, Mile23, subhojit777, tibbsa, Ayesh: Clean-up system module test members - ensure property definition and use of camelCase naming convention

Issue #2461063 by Wim Leers, effulgentsia: AJAX forms using #ajax broken when page caching is enabled

Issue #1919930 by tim.plunkett, nlisgo: Bundle entity form IDs violate module namespaces (both on server-side + front-end CSS)

Issue #1987612 by valthebald, Mile23, aspilicious, Pinolo, InternetDevels: Convert ajax_test_dialog_contents() to a new style controller

Issue #784626 by Wim Leers, Manuel Garcia, jcisio, joelpittet, Bevan, fcaspani, dcmouyard: Default all JS to the footer, allow asset libraries to force their JS to the header

Issue #2368797 by Wim Leers, dawehner, rteijeiro: Optimize ajaxPageState to keep Drupal 8 sites fast on high-latency networks, prevent CSS/JS aggregation from taking down sites and use HTTP GET for AJAX requests

Issue #2395395 by alexpott, effulgentsia, Gábor Hojtsy: TestBase lacks a config method to be used consistently in tests

Issue #2384545 by Wim Leers, jbrown: $element['#ajax']['callback'] is broken, hence breaking e.g. inserting images in CKEditor

Issue #2378095 by Wim Leers, Devin Carlson: Convert all remaining attached individual CSS/JS assets to attached asset libraries

Issue #2328111 by dawehner, martin107, neclimdul: Replace most instances of the DRUPAL_ROOT constant with the app.root container parameter.

Issue #2242749 by znerol, torotil, rszrama, larowlan, dawehner, penyaskito, tim.plunkett, sun, Damien Tournoud, David_Rothstein,  effulgentsia: Fixed Port Form API security fix SA-CORE-2014-002 to Drupal 8.

Issue #2312093 by alexpott, yched, andypost, swentel | xjm: Rename FieldInstanceConfig to FieldConfig.

Issue #2273277 by Wim Leers, effulgentsia, Fabianx: Fixed Figure out a solution for the problematic interaction between the render system and the theme system when using #pre_render.

Issue #2287727 by yched, swentel, alexpott: Rename Field[instance]Config classes and entity types (again).

Issue #697760 by sun: Replace getInfo() in tests with native phpDoc + annotations (following PHPUnit).

Issue #2143291 by plach, alexpott, xjm, effulgentsia, pwolanin, swentel | yched: Clarify handling of field translatability.

Issue #2080343 by connork, izus, rahul.shinde, lokapujya | mrsinguyen: Remove Unused local variables from system module.

Issue #2113911 by LewisNyman, Manuel Garcia, longwave, nod_, Rajendar Reddy, pakmanlh, olemedia, rteijeiro: Modal style update.