tree 6fce2ba39e917644900118008036992a63b1668d
parent d7748bd81f2bb86c7a445eda089bf8dac15e1aab
author Luca Milanesio <luca.milanesio@gmail.com> 1609973187 +0000
committer Luca Milanesio <luca.milanesio@gmail.com> 1610374085 +0000

Add shadow-selection-polyfill

The selection on shadow-DOM is not implemented
in Safari and the document.getSelection() fallback
is not suitable for use.

The GoogleChromeLabs provided a library to solve
the problem: shadow-selection-polyfill.

What the library does is to manage the selection
change events and calculate and cache the results
for the shadow root elements, creating a custom
event '-shadow-selectionchange' once the selection
has been completed.

There is one gotcha that makes things slightly
more complicated: what the library provides is a Range
and not a Selection object. There are a couple of
adjustments needed in gr-diff and gr-diff-highlight
to use the range directly instead of getting it
from the selection.

NOTE: Even though the shadow-selection-polyfill could
also manage Chrome and Firefox, keep the existing
logic to avoid any possible regression, which is not
desireable on a stable branch.

On stable-3.1, because of the problems related to the inclusion
of the dependency via Bower, shadow.js has been removed
from its exports and used as pure JS file included in the
gr-diff.html.

This change needs would not be applied to stable-3.2 where,
thanks to the npm package mangement, it would be consumed
from the NPM registry directly.

Bug: Issue 11811
Change-Id: I41c4e94343010972c8a9f0f1ba3a059ca7af5292