Copy EditorClientImpl.{cpp,h} to UndoStack.{cpp,h}

This patch is a preparation part of introducing UndoStack class in editing module. Another patch, http://crrev.com/74753003, updates GYP file and brings integration.

BUG=n/a
TEST=n/a; no behavior changes

Review URL: https://codereview.chromium.org/65563004

git-svn-id: svn://svn.chromium.org/blink/trunk@162332 bbb929c8-8fbe-4397-9dbb-9b2b20218538
We should update associated text render object in Node::normalize()

This patch changes to update associated text render object for text node being merged into another node. Before this patch, Text::mergeNextSiblingNodesIfPossible(), which is called by Node::normalize() and merges text nodes, updates associated character data to empty, although it didn't update associate text render object. This led TextIterator used old text data and called Range::create() with wrong parameter.

BUG=306526
TEST=LayoutTests/fast/dom/Text/normalize-crash-in-spell-checker.html

Review URL: https://codereview.chromium.org/66973008

git-svn-id: svn://svn.chromium.org/blink/trunk@162333 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Make pass/fail more obvious in some animation and transition tests

R=shans

Review URL: https://codereview.chromium.org/75963005

git-svn-id: svn://svn.chromium.org/blink/trunk@162334 bbb929c8-8fbe-4397-9dbb-9b2b20218538