fix FF contenteditable backspace bug.
https://github.com/yui/yui3/issues/1376
tweaks per YUI team advice on pull request.

https://github.com/yui/yui3/pull/1502
tweaks per YUI team advice on pull request.

https://github.com/yui/yui3/pull/1502
[yui] Deprecate modules list page

All modules list has been posted on this page so far, but because
it is possible to see a list of equivalent even API Docs, the need
for us to provide this page is low now. Fix #619.
[docs] Tweak README

Fix our repository URL on GitHub.
Addressed issue with path chaining in canvas implementation of graphics. Fix #1565
Merge branch 'rm-modules-list' into live-docs
[docs] Document usage of username/password in Y.io config. Fix #1572
Merge remote-tracking branch 'customcommander/docs-io-auth' into live-docs
[docs] Fix typo in docs for event-custom
[core] Fix value of `this` inside ES6 module definitions
[Loader] : Addition of `calculate` to performance tests.
[Loader] : Refactor of performance tests.
[Loader] : Update five tests.
[Loader] : Rewrite of `_sort`.
[node] Remove Node and NodeList methods duplicate comments

getAttribute() and setAttribute() methods of Node and NodeList
definition by comments for API Docs are duplicated. Fix #1604.
Merge branch 'fix1604' into live-docs
[node] Build

min files is no changes.
Merge branch 'es6-context' into dev-master
[dom] Normalize setting a node value to null

When set a node value to `null`, then a node value returns `"null"` as string
on the legacy IE (IE <= 9). A node value returns an empty string on the modern
browsers (Chrome, Firefox, IE >= 10). This change is to normalize the results
of setting a node value to `null` on any browsers. Fix #1603.