Merge branch 'master' into v4

Conflicts:
	.gitignore
	Gruntfile.js
	_config.yml
	dist/css/bootstrap-theme.css
	dist/css/bootstrap-theme.min.css
	dist/css/bootstrap.css
	dist/css/bootstrap.css.map
	dist/css/bootstrap.min.css
	dist/js/bootstrap.js
	dist/js/bootstrap.min.js
	docs/_includes/components/navbar.html
	docs/_includes/components/progress-bars.html
	docs/_includes/css/grid.html
	docs/_includes/css/overview.html
	docs/_includes/customizer-variables.html
	docs/_includes/getting-started/accessibility.html
	docs/_includes/getting-started/browser-device-support.html
	docs/_includes/getting-started/community.html
	docs/_includes/getting-started/disabling-responsiveness.html
	docs/_includes/getting-started/download.html
	docs/_includes/getting-started/examples.html
	docs/_includes/getting-started/license.html
	docs/_includes/getting-started/third-party-support.html
	docs/_includes/js/alerts.html
	docs/_includes/js/buttons.html
	docs/_includes/js/carousel.html
	docs/_includes/js/collapse.html
	docs/_includes/js/dropdowns.html
	docs/_includes/js/modal.html
	docs/_includes/js/popovers.html
	docs/_includes/js/scrollspy.html
	docs/_includes/js/tabs.html
	docs/_includes/js/tooltips.html
	docs/_includes/js/transitions.html
	docs/_includes/nav/javascript.html
	docs/_includes/nav/main.html
	docs/about.html
	docs/assets/css/docs.min.css
	docs/assets/css/src/docs.css
	docs/assets/js/customize.min.js
	docs/assets/js/raw-files.min.js
	docs/assets/js/src/customizer.js
	docs/dist/css/bootstrap-theme.css
	docs/dist/css/bootstrap-theme.min.css
	docs/dist/css/bootstrap.css
	docs/dist/css/bootstrap.css.map
	docs/dist/css/bootstrap.min.css
	docs/dist/js/bootstrap.js
	docs/dist/js/bootstrap.min.js
	docs/migration.html
	js/affix.js
	js/alert.js
	js/button.js
	js/carousel.js
	js/collapse.js
	js/dropdown.js
	js/modal.js
	js/popover.js
	js/scrollspy.js
	js/tab.js
	js/tests/unit/affix.js
	js/tests/unit/button.js
	js/tests/unit/carousel.js
	js/tests/unit/modal.js
	js/tests/unit/tooltip.js
	js/tests/visual/modal.html
	js/tooltip.js
	less/component-animations.less
	less/jumbotron.less
	less/mixins/background-variant.less
	less/mixins/buttons.less
	less/mixins/responsive-visibility.less
	less/mixins/text-emphasis.less
	less/navbar.less
	less/navs.less
	less/scaffolding.less
	less/tooltip.less
	less/utilities.less
	less/variables.less
	package.json
	scss/_buttons.scss
	scss/_forms.scss
	scss/_modal.scss

Gruntfile.js

@@ -246,6 +246,9 @@ module.exports = function (grunt) {
 
     cssmin: {
       options: {
+        // TODO: disable `zeroUnits` optimization once clean-css 3.2 is released
+        //    and then simplify the fix for https://github.com/twbs/bootstrap/issues/14837 accordingly
+        compatibility: 'ie8',
         keepSpecialComments: '*',
         noAdvanced: true
       },
@@ -341,7 +344,7 @@ module.exports = function (grunt) {
     watch: {
       src: {
         files: '<%= jshint.core.src %>',
-        tasks: ['jshint:src', 'qunit', 'concat']
+        tasks: ['jshint:core', 'qunit', 'concat']
       },
       test: {
         files: '<%= jshint.test.src %>',