Give the focus back to the editor after using a wiki editor toolbar button

Steps to reproduce:

1. Edit a page with the Wiki editor, with Syntax Highlighting enabled
2. Select a word in the content
3. Click the Bold toolbar button, or reach it with the keyboard and press Enter
4. Type some text

Expected result: the typed text is inserted in the content, after the bold markup.

Actual result: the bold markup is inserted, but the focus stays on the toolbar button, so the typed text is lost until the user clicks back in the editor.

Without Syntax Highlighting, the toolbar gives the focus back to the wiki editor's textarea after inserting the markup. The Syntax Highlighting insert function doesn't do it for the CodeMirror editor.