Revert "Implement basic Left/Right visual caret movement with bidi caret affinity"

This reverts commit d7d46e615e305e3c3cc927539c553e9c711abf7a.

Reason for revert: This patch may be the cause of failing tests:
* virtual/bidi-caret-affinity/editing/selection/modify_move/move_left_word_04_rtl_multi_line.html
* virtual/bidi-caret-affinity/editing/selection/modify_move/move_right_word_02_ltr_multi_line.html
* virtual/bidi-caret-affinity/editing/selection/move-bidi-isolate.html
on Mac 10.11. See bug for more details.

Bug: 920878

Original change's description:
> Implement basic Left/Right visual caret movement with bidi caret affinity
> 
> Design doc: http://bit.ly/2QVAwGq
> 
> This patch:
> 
> 1. Introduces a new structure NGCaretNavigator to index the bidi
>    information of the text_content of a block. The structure is
>    built together with NGOffsetMapping.
> 
> 2. With NGCaretNavigator, we can test bidi boundary in VisiblePosition
>    canonicalization more directly.
> 
> 3. With NGCaretNavigator, left/right visual movements on text_content
>    are implemented in a straightforward manner. This patch implements
>    only the basics: one line of plain text. However, the most complicated
>    part of the legacy implementation, namely *bidi and whitespace
>    collapsing*, have already been naturally handled.
> 
> 4. SelectionModifierCharacter adds a new branch where bidi caret
>    affinity is enabled, and uses NGOffsetMapping to convert input/output
>    between DOM and NGCaretNavigator.
> 
> Note that the implementation works on both legacy and NG layout.
> 
> Bug: 894651
> Change-Id: I806ce23a97b2dfd977d6eecfd224c812319e6a7e
> Reviewed-on: https://chromium-review.googlesource.com/c/1377618
> Commit-Queue: Xiaocheng Hu <xiaochengh@chromium.org>
> Reviewed-by: Yoshifumi Inoue <yosin@chromium.org>
> Reviewed-by: Yoichi Osato <yoichio@chromium.org>
> Reviewed-by: Emil A Eklund <eae@chromium.org>
> Reviewed-by: Koji Ishii <kojii@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#621807}

TBR=yosin@chromium.org,eae@chromium.org,yoichio@chromium.org,kojii@chromium.org,xiaochengh@chromium.org

Change-Id: I7146445c16b13d3cdaf12e2f88b78353b7f0d10a
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 894651
Reviewed-on: https://chromium-review.googlesource.com/c/1405116
Reviewed-by: Patti <patricialor@chromium.org>
Commit-Queue: Patti <patricialor@chromium.org>
Cr-Commit-Position: refs/heads/master@{#621881}
133 files changed