There is no one who is familiar with CSSOM in dom-team 
Who is familiar CSSOM's Range.getBoundingClientRect()?

I'm working this.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/816c5e63c869a200146fa3c7bff8c3fb776fd381

commit 816c5e63c869a200146fa3c7bff8c3fb776fd381
Author: Yoshifumi Inoue <yosin@chromium.org>
Date: Tue Aug 22 10:00:17 2017

Refactor Range::GetBorderAndTextQuads()

This patch changes |Range::GetBorderAndTextQuads()| to utilize early-continue
style, const pointer and const variable for improving source code readability.

Bug:  757720 
Change-Id: I0f3b1cfb9eb7971da94133df55c1e337fb36556e
Reviewed-on: https://chromium-review.googlesource.com/625554
Reviewed-by: Kent Tamura <tkent@chromium.org>
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496267}
[modify] https://crrev.com/816c5e63c869a200146fa3c7bff8c3fb776fd381/third_party/WebKit/Source/core/dom/Range.cpp

Removing Blink>CSS component for now to clarify issue ownership. Please add back when action is required from the style team, thanks!

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6c2da57b3c46943f9c4fafe3f1082c44f9b043ba

commit 6c2da57b3c46943f9c4fafe3f1082c44f9b043ba
Author: Yoshifumi Inoue <yosin@chromium.org>
Date: Wed Aug 23 09:59:42 2017

Make Range::GetBorderAndTextQuads() to support ::first-letter

This patch makes |Range::GetBorderAndTextQuads()| to support ::first-letter
CSS pseudo-element.

In layout tree, ::first-element is represented by two |LayoutTextFragment|,
which is derived from |LayoutText|, objects instead of one |LayoutText|. Each
|LayoutTextFragment| object contains first-letter part and remaining part.
|Node::GetLayoutObjeect()| for |Text| node returns remaining part.

Before this patch, |Range::GetBorderAndTextQuads()| processes only remaining
part. After this patch, |Range::GetBorderAndTextQuads()| processes both
first-letter part and remaining part.

Bug:  757720 
Change-Id: Ic6038a4a50a04c45c500559ee020644f0e6468ad
Reviewed-on: https://chromium-review.googlesource.com/625857
Commit-Queue: Yoshifumi Inoue <yosin@chromium.org>
Reviewed-by: Koji Ishii <kojii@chromium.org>
Cr-Commit-Position: refs/heads/master@{#496643}
[modify] https://crrev.com/6c2da57b3c46943f9c4fafe3f1082c44f9b043ba/third_party/WebKit/Source/core/dom/Range.cpp
[modify] https://crrev.com/6c2da57b3c46943f9c4fafe3f1082c44f9b043ba/third_party/WebKit/Source/core/dom/RangeTest.cpp