The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/1aee657f2d27df3cad42453428b527f592d29885

commit 1aee657f2d27df3cad42453428b527f592d29885
Author: luoe <luoe@chromium.org>
Date: Fri Sep 16 18:35:43 2016

DevTools: fix ViewportControl's text selection logic

ViewportControl's _selectedText currently does this:
1 - get a selection+range with native window/shadowRoot.getSelection()
2 - calculate first and last viewport items that are part of the selection
3 - get the deepTextContent() of all those items
4 - trim out text based on the offsets provided by the selection

Step 4 is done by _textOffsetInNode(), which takes an itemElement, container,
and offset. Beforethis CL, it would start at the item and traverse all text
nodes until it stops at the container (node !== container). In this logic, it
assumes that the container is a text node itself so that (node !== container)
will be false and we will stop before counting the container's text length. In
reality, a user can drag to create a selection where the
range.start/endContainer can be an element that is not a text node (e.g. <span>
containing a text node). Then, _textOffsetInNode() would continue to traverse
and node.traverseNextTextNode() will never return a node that is === container.
This results in extra text length being counted which breaks the offset logic.

This CL makes sure that in those cases where the range.start/endContainer is not
a text node, such as a <span> containing the boundary text, we will stop
traversing when we hit a text node that is the end or is a descendant.

BUG= 647287 

Review-Url: https://codereview.chromium.org/2340223002
Cr-Commit-Position: refs/heads/master@{#419227}

[modify] https://crrev.com/1aee657f2d27df3cad42453428b527f592d29885/third_party/WebKit/LayoutTests/inspector/console/console-viewport-selection-expected.txt
[modify] https://crrev.com/1aee657f2d27df3cad42453428b527f592d29885/third_party/WebKit/LayoutTests/inspector/console/console-viewport-selection.html
[modify] https://crrev.com/1aee657f2d27df3cad42453428b527f592d29885/third_party/WebKit/Source/devtools/front_end/ui/ViewportControl.js