Update less.js to v1.6.3.
Update dependencies.
Merge pull request #12718 from twbs/dependencies

Update dependencies.
Merge pull request #12719 from twbs/update-less

Update less.js to v1.6.3.
Add build-raw-files log; fixes #12603

Fixes #12672
bump grunt-exec to v0.4.5 & add missing tilde to version spec
regenerate npm-shrinkwrap.canonical.json
Merge branch 'master' into amplego-element-method-compat