Issue #3425337 by mondrake: Fix root namespace classes DebugClassLoader forward compatibility warnings

Revert "Issue #3425337 by mondrake: Fix root namespace classes DebugClassLoader forward compatibility warnings"

This reverts commit ea9cc753.

Issue #3425337 by mondrake: Fix root namespace classes DebugClassLoader forward compatibility warnings

Revert "Issue #3425337 by mondrake: Fix root namespace classes DebugClassLoader forward compatibility warnings"

This reverts commit ff7c5de3.

Issue #3425337 by mondrake: Fix root namespace classes DebugClassLoader forward compatibility warnings

Issue #3266568 by mxr576, sourabhjain, quietone: Refactor array_merge() usage in loops as possible for performance

Issue #3106216 by Spokje, longwave, alexpott, apaderno, Hardik_Patel_12, daffie: Remove unused variables from core

Issue #3014121 by Geordi, shreyakaushik11, anmolgoyal74, msankhala, rwohleb, rachel_norfolk, akanksha-hp, jhodgdon: Attribute.php code snippet not properly escaped

Issue #2851394 by GoZ, hgunicamp, oknate, jungle, wolffereast, tameeshb, mmatsoo, ridhimaabrol24, jofitz, swarad07, tanc, shaktik, dimaro, shashikant_chauhan, MerryHamster, quietone, nitesh624, martin_q, boaloysius, gaurav.kapoor, nitvirus, ankithashetty, Munavijayalakshmi, kostyashupenko, leolando.tan, amit.drupal, ravi.shankar, akashkrishnan01, Swapnil_Kotwal, Saviktor, mrinalini9, anmolgoyal74, Venkatesh Rajan.J, shimpy, lomasr, Dinesh18, shubham.prakash, mahtab_alam, markdorison, cilefen, longwave, bleen, xjm, alexpott, gmaltoni: Fix grammar 'a' to 'an' when necessary

Issue #3090145 by mondrake, andralex, alexpott, amateescu, andypost, longwave: Ensure that mixing array and Attribute objects in theme rendering is managed properly

Issue #2572605 by Gábor Hojtsy, slasher13, Jo Fitzgerald, alexpott, andypost, Cottser, skyredwang, mfernea, joelpittet, jibran, larowlan, aleevas, Wim Leers, lauriii, catch, Berdir: Make Drupal 8 optionally working with Twig 2, while keeping its dependency on Twig 1

Issue #2776975 by joelpittet, dawehner, tim.plunkett, xjm, pfrenssen: March 3, 2017: Convert core to array syntax coding standards for Drupal 8.3.x RC phase

Issue #2706669 by alexpott, tstoeckler: Fix Drupal.Functions.FunctionDeclaration.* coding standards in core

Issue #2665992 by alexpott, klausi, heykarthikwithu, xjm, tstoeckler: @file is not required for classes, interfaces and traits

Issue #2579691 by lauriii, alexpott, stefan.r, YesCT, dawehner: Remove usages of SafeMarkup::isSafe()

Issue #2605420 by IRuslan, joelpittet: Missing aria-pressed template_preprocess_details() due to lost copied attributes in Attribute

Issue #2502621 by Pravin Ajaaz, hussainweb, Peacog, jhodgdon, ivanjaros: Replace implement notes with inheritdoc tag

Issue #2515018 by joshi.rohit100, sdstyles, joelpittet: Lowercase the instances of camelcase'd instanceOf in core for consistency

Issue #2576533 by alexpott, stefan.r, Wim Leers, dawehner, xjm, effulgentsia, catch: Rename SafeStringInterface to MarkupInterface and move related classes

Issue #2559971 by stefan.r, alexpott, lauriii, nlisgo, plach, dawehner: Make SafeMarkup::format() return a safe string object to remove reliance on a static, unpredictable safe list

Issue #2567741 by mr.baileys: Attribute/drupal_attributes() docs do not mention protocol filtering on URLs

Issue #2557113 by stefan.r, alexpott, dawehner, joelpittet, cilefen, lauriii, plach, catch, chx, xjm: Make t() return a TranslationWrapper object to remove reliance on a static, unpredictable safe list

Issue #2559969 by alexpott: Make SafeStringInterface extend \JsonSerializable so we don't have to do so much string casting

Issue #2506151 by joelpittet, Cottser, lauriii, Lukas von Blarer, tim.plunkett: Make the Twig extension link() accept Attribute objects

Issue #2506133 by alexpott, joelpittet, dawehner, pwolanin: Replace SafeMarkup::set() in \Drupal\Core\Template\Attribute

Issue #2505701 by pwolanin, YesCT, akalata: Document SafeMarkup::set and Use htmlspecialchars() directly in Attribute() so we don't bloat the list of safe strings

Issue #2457887 by prateekMehta, stefan.r, rpayanm, alexpott: Use Utility\SafeMarkup class instead of Utility\String for placeholder(), checkPlain(),format() functions

Issue #2325517 by lauriii, Alienpruts, Tom Verhaeghe, joelpittet, rteijeiro | Cottser: Add methods for adding/removing attributes (not classes) on Attribute objects.

Issue #2347511 by davidhernandez, lauriii, rpayanm, kasn: Add method to test if class attribute has class on Attribute object.

Issue #2336355 by alexpott, Cottser: Fixed Refactor Attribute rendering so that class= is not printed.

Issue #2290143 by cs_shadow, amitgoyal, er.pushpinderrana, xjm: Improve the class documentation of \Drupal\Core\Template\Attribute.

Issue #2285451 by joelpittet, davidhernandez, cilefen, mdrummond, mortendk: Create addClass() and removeClass() methods on Attribute object for merging css class names.

Issue #1825952 by Fabianx, joelpittet, bdragon, heddn, chx, xjm, pwolanin, mikey_p, ti2m, bfr, dags, cilefen, scor, mgifford: Turn on twig autoescape by default

Issue #2227869 by joelpittet: Remove magic printing from Attribute class to make Twig 'without' filter work for attributes.

Issue #2212309 by joelpittet: Drupal\Core\Template and twig.engine docs, coding standards, and unused code cleanup.

Issue #2006282 by joelpittet: Refactor Attribute classes - Cleanup, Security, and Readability and minor performance.