Revert "Issue #2225681 by quietone, Jo Fitzgerald, dipakmdhrm, Adita, maxocub, Gábor Hojtsy, phenaproxima, iMiksu, Manuel Garcia, catch: Migrate D6 i18n blocks translated strings"

This reverts commit b53e50d7.

Issue #2225681 by quietone, Jo Fitzgerald, dipakmdhrm, Adita, maxocub, Gábor Hojtsy, phenaproxima, iMiksu, Manuel Garcia, catch: Migrate D6 i18n blocks translated strings

Issue #2917883 by quietone, TR, Jo Fitzgerald, masipila, phenaproxima: Rename 'migration_templates' directories in core modules to 'migrations'

Issue #2572787 by alexpott, mfernea, attiks, andriyun, andypost, RoSk0, hussainweb, klausi, martin107: Fix 'Drupal.WhiteSpace.CloseBracketSpacing' coding standard

Issue #2873696 by nvexler, wengerk, gido, Jo Fitzgerald, xjm: Add @internal to core classes, methods, properties to Form Classes

Issue #2901726 by mfernea, gmario, finn.lewis, robertoperuzzo, rachel_norfolk: Fix 'Squiz.Functions.MultiLineFunctionDeclaration' coding standard

Issue #2782833 by Mile23, martin107, larowlan, effulgentsia: Remove usages of deprecated EntityManager from Entity class

Issue #2825078 by Mile23, dawehner, Wim Leers, Gábor Hojtsy: Deprecate UnitTestCase dependency on block module

Issue #2572791 by Mile23, andriyun, attiks, RoSk0: Fix 'Drupal.WhiteSpace.OpenBracketSpacing' coding standard

Issue #2901739 by andriyun, Jo Fitzgerald, mfernea, xjm: Fix 'Squiz.Arrays.ArrayDeclaration' coding standard

Issue #2803621 by Mile23: Break BrowserTestBase & children dependency on Simpletest, deprecate stub BC traits

Issue #2569805 by quietone, Jo Fitzgerald, mikeryan, joelpittet, heddn, Adita, Miguel.kode, iMiksu, tvb, maxocub, juancasantito, phenaproxima, alexpott, neclimdul, xjm: For Drupal migration, identify the source module

Issue #2805205 by andrewmacpherson, michielnugter, lauriekap, BarisW, pk188, Ehud, arunkumark, SteffenR, Lendude, droplet, alexpott, xiwar: Provide screen-reader feedback when filtering by block name

Issue #2352791 by prics, sam0971, naveenvalecha, Ashish.Dalvi, dstotijn, ZeiP, Mile23, tim.plunkett: Add test coverage for admin/structure/block/demo

Issue #2878548 by alexpott, droplet, Cottser, idebr, joelpittet, xjm, martin107: Fix CSS whitespace issues

Issue #2873752 by misselbeck, johnshortess: Add change record to @deprecated code for BlockPluginInterface

Issue #2824610 by quietone, Jo Fitzgerald, ohthehugemanatee, heddn, catch: Rename DedupeBase/DedupeEntity process plugins to MakeUnique and add documentation

Issue #2422229 by quietone, ultimike, vprocessor, anish.a, Jo Fitzgerald, phenaproxima: D6->D8 Core block migrations missing settings tests

SA-CORE-2017-001 by alexpott, benjy, Berdir, casey, cilefen, dawehner, Heine, klausi, larowlan, Mixologic, mlhess, pwolanin, samuel.mortenson, Wim Leers, xjm, YesCT

Issue #2854529 by alexpott, xjm, klausi, Chi, Mixologic: Fix Drupal.Scope.MethodScope - all methods should have scopes

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 #2580935 by vaplas, maijs: DisplayPluginBase::applyDisplayCachablityMetadata() method has typo in it's name

Issue #2770921 by dawehner, klausi, Mile23, mpdonadio, xjm, claudiu.cristea: Feb 21st: Convert chunk of WTB to BTB by just moving classes, changing use statements adding traits

Issue #2287073 by Berdir, slashrsm, Denchev, jibran, Thew, dasjo, andypost, Arla, zaporylie, marvin_B8, piyuesh23, EclipseGc: Allow views contextual filters to expose the context using argument validation plugins