Make FrameSelection to hold non-canonicalized DOM positions
This patch makes |FrameSelection| to hold non-canonicalized DOM positions in
|SelectionEditor| to align Selection API specification[1] for improving
interoperatbility[2].
Before this patch we holds selection as |VisibleSelection| as canonicalized
DOM positions. This behavior is not align with Selection API specification[1]
then the most complained issue of Blink from editing-tf@w3c.
The heart of this patch is holding selection as |SelectionInDOMTree| and
compute |VisibleSelection| on-demand with cache of computed |VisibleSelection|.
|VisibleSelection| cache is invalidate each DOM tree change and style change
since canonicalization referes CSS style properties, e.g display, visibility,
-webkit-user-modify, etc, and layout dimension.
|SelectionEditor| utilizes |SynchronousMutationObserver| to relocate
|m_selectionInDOMTree| instead of |FrameSelection|. Before this patch
|FrameSelection| relocates |VisibleSelection| with dirty layout tree then
sets |FrameSelection::setSelection()|. To void cyclic reference between
|FrameSelection| and |SelectionEditor|, we could not move relocation part to
|SelectionEditor|.
This patch also updates
|FrameSelection::updatePostionAfterAdoptingTextNodesMerged()| to handle
|PositonAnchorType|.
# Highlight of changes
## FrameCaret
- Compute caret position after "layout clean" rather than each selection change
to align rendering pipeline.
## CharacterData
Changes timing of notifying character data update for ease of relocation of
positions.
## FrameSelection
- Move |m_isHandleVisible| to |SelectionInDOMTree| as follow-up of [5].
- Move selection relocation to |SelectionEditor|; following patch will move
implementations to "SelectionEditor.cpp"
## SelecitonEdtior
- Make it to hold |SelectionInDOMTree| with relocation at DOM mutation.
- Caching |VisibleSelection|
# Brief description of test expectation changes:
## ImeTest.java:
This patch gets rid of redundant selection change event from
- |testImePaste|,
- |testContentEditableEvents_DeleteSurroundingText|
- |testInputTextEvents_DeleteSurroundingText|
## LayoutTests
Before this patch, Blink uses |VisibleSelection| when it sets even if style and
layout changed. This is wrong and unexpected behavior since positions in
|VisibleSelection| can no longer be canonicalized positions. This patch changes
this behavior to return "sane" canonicalized positions with clean style and
layout tree.
This patch is the result of many attempts. Previous changes can be found in
[3][4].
Convert layout test move-up-down-should-skip-hidden-elements.html to performance test
This patch converts layout test "move-up-down-should-skip-hidden-elements.html"
to performance tests, move line up and move line down, since this layout test
measures verifies execution speed regression. Using performance test is easier
to track performance regression than detecting timeout in layout test.
