Remove FrameLoader::shouldTreatURLAsSameAsCurrent

This function is essentially unchanged since it was moved to C++ in http://src.chromium.org/viewvc/blink?revision=18541&view=revision

It includes a clause where we check the original url as well as the actual url to determine if we should treat the URL as same. This is counter-intuitive and unnecessary. Replace all shouldTreatURLAsSameAsCurrent() with checks against the new DocumentLoader::urlForHistory(), which checks either the url or the SubstituteData::failingURL() if one exists.

This is also the only use of HistoryItem::m_originalURLString, so remove that, too.

BUG=340277
TEST=http/tests/navigation/back-to-get-after-post.php

Review URL: https://codereview.chromium.org/154213002

git-svn-id: svn://svn.chromium.org/blink/trunk@167971 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove the TextTrackCue constructor

Intent to Remove:
https://groups.google.com/a/chromium.org/d/msg/blink-dev/R34xpMQGtXU/XwXsi85Y7acJ

BUG=346235

Review URL: https://codereview.chromium.org/177613005

git-svn-id: svn://svn.chromium.org/blink/trunk@167972 bbb929c8-8fbe-4397-9dbb-9b2b20218538