Issue #2512452 by dawehner, pwolanin, alexpott, fnqgpc: Confirm form cancel button can lead to external domain

Revert "Issue #2512452 by dawehner, pwolanin, fnqgpc: Confirm form cancel button can lead to external domain"

This reverts commit 1462460f.

Issue #2512452 by dawehner, pwolanin, fnqgpc: Confirm form cancel button can lead to external domain

Issue #2335661 by Wim Leers, pwolanin, dawehner, Fabianx, larowlan, catch, Berdir: Outbound path & route processors must specify cacheability metadata

Issue #2426181 by effulgentsia, mpdonadio, xjm: Add a Url::fromUserInput() wrapper method for generating URLs from user-entered paths

Issue #2423579 by mpdonadio, xjm, heilop, Wim Leers, webchick: Url::fromUrl('user-path:/') should throw an exception when a path component without a slash is given

Issue #2417647 by Wim Leers, effulgentsia: Add leading slash to paths within 'user-path:' URIs, to allow 'user-path:' URIs to point to the <none> route

Issue #2418613 by pwolanin: Fix #0 bug in toUriString() method in Url class, clarify toString() vs toUriString()

Issue #2418139 by pwolanin, kgoel, dawehner, almaudoh, Wim Leers: Add a toUriString method to Url class and add a route: scheme

Issue #2417333 by Wim Leers, pwolanin, xjm, dawehner: Add support for user-path: scheme to Url class

Issue #2411333 by almaudoh, hussainweb, Wim Leers, pwolanin, larowlan, dawehner, RavindraSingh, jibran: Create standard logic to handle a entity: URI scheme

Issue #2235457 by dawehner, amateescu, hussainweb, Berdir, benjy, Wim Leers, lokapujya, RavindraSingh, Ryan Weal, jibran, Jalandhar: Use link field for shortcut entity

Issue #2362227 by dawehner, mpdonadio, znerol, tim.plunkett, skipyT: Replace all instances of current_path()

Issue #2350507 by hussainweb, hctom, jbrown: Fixed \Drupal\Core\Url has no __toString() magic method.

Issue #2347465 by tim.plunkett, dawehner, cilefen: Convert all instances of #type link/links to convert to use routes.

Issue #2343759 by pwolanin, larowlan, dawehner, tim.plunkett, effulgentsia, xjm, Wim Leers: Provide an API function to replace url()/l() for external urls.

Issue #2330751 by dawehner, chx: Fixed Random test failures everywhere due to ->with(Request::create()).

Issue #2322809 by chx, dawehner, tim.plunkett: Tighten routing security by access checking in matchRequest.

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

Issue #2054011 by amateescu, pwolanin, dawehner, YesCT, tim.plunkett, blueminds, Berdir, das-peter, effulgentsia: Implement built-in support for internal URLs.