Widgets: Extend the Text widget with TinyMCE.

Introduces rich text formatting: bold, italic, lists, links.

Props westonruter, azaozz, timmydcrawford, obenland, melchoyce.
See #35760.
Fixes #35243.

Built from https://develop.svn.wordpress.org/trunk@40631


git-svn-id: http://core.svn.wordpress.org/trunk@40492 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/css/customize-widgets.css

@@ -213,6 +213,21 @@
 	display: block;
 }
 
+/* Text Widget */
+.wp-customizer div.mce-inline-toolbar-grp,
+.wp-customizer div.mce-tooltip {
+	z-index: 500100 !important;
+}
+.wp-customizer .ui-autocomplete.wplink-autocomplete {
+	z-index: 500110; /* originally 100110, but z-index of .wp-full-overlay is 500000 */
+}
+.wp-customizer #wp-link-backdrop {
+	z-index: 500100; /* originally 100100, but z-index of .wp-full-overlay is 500000 */
+}
+.wp-customizer #wp-link-wrap {
+	z-index: 500105; /* originally 100105, but z-index of .wp-full-overlay is 500000 */
+}
+
 /**
  * Styles for new widget addition panel
  */