Issue #1431658 by Albert Volkman, xjm, kid_icarus, ChinggizKhan, rgristroph, connork: Massive API docs cleanup for system tests

Issue #1805776 by psynaptic, Eric_A, rbayliss: Fixed Fatal error: Class 'Drupal\Core\Template\ArrayIterator' not found in core/lib/Drupal/Core/Template/Attribute.php.

Issue #1362974 by droplet, dcam, Jacine, tkrajcar: Remove type='text/javascript' from <script> tags.

Issue #1700382 by Albert Volkman, cam8001: Replace remaining references to drupal_attributes() with new Attributes().

Issue #1764634 by tim.plunkett, nod_: Fixed Drupal.settings is only populated if a custom setting is added.

Issue #1737148 by nod_, SebCorbin, larowlan, tim.plunkett, Albert Volkman, nick_schuch, sun: Explicitly declare all JS dependencies, don't use drupal_add_js().

Issue #1739994 by pp, das-peter, Gábor Hojtsy: Use the Language class universally instead of stdObj instances.

Issue #1669902 by alexpott, aspilicious, sun: Adjust system.performance configuration for new guidelines.

Issue #1392208 by Gábor Hojtsy, penyaskito, David_Rothstein: Fixed Impossible to install Drupal in a non-English language when following the provided instructions.

Issue #562042 by cburschka, Rob Loach, sun, scor: Added Search for install profiles in sites/[all|site]/profiles folders, and move core profiles into /core/profiles.

Issue #1711070 by kid_icarus, tim.plunkett, xjm, droplet, zendoodles and cam8001: Convert tests to use ::$modules property instead of parent::setUp($modules).

Using the language_manager wrapper function to return a language whether or not we're in the requet scope

- Patch #1290694 by hefox, tlattimore, c4rl, chx, tim.plunkett, tstoeckler, msonnabaum: provide consistency for attributes and classes arrays provided by template_preprocess().

Issue #1493108 by marcingy, Mike Wacker, sun, kbasarab, Berdir, Rok Žlender, cosmicdreams, alexpott: Convert logging and error settings to configuration system.

Issue #1071818 by JeremyFrench, nod_, reglogge, anthbel, xjm, sun, NROTC_Webmaster, lliss, Cottser: Fixed Lazy-loading CSS fails in IE.

- Patch #1211668 by scito, Devin Carlson, bornholtz: special characters are encoded twice for feed icon attribute title.

Issue #1496542 by cosmicdreams, sun, chx, vasi1186, aspilicious, alexpott, nadavoid, Pedro Lozano, disasm, andypost | heyrocker: Convert site information to config system.

- Patch #1510686 by cosmicdreams, vasi1186, webflo, disasm: replace remaining references to global () with drupal_container().

Issue #1561004 by marcingy, aries, yurtboy, Tor Arne Thune: Many tests still reference locale although they only need language module.