TypeScript: fix keywords in conditional expressions

Summary:
Now, keywords are highlighted before ":" in conditional expressions, for example:

a = b ? false : true;

Reviewers: Framework: Syntax Highlighting, dhaumann, cullmann

Reviewed By: Framework: Syntax Highlighting, cullmann

Subscribers: kwrite-devel, kde-frameworks-devel

Tags: Kate, Frameworks

Differential Revision: https://phabricator.kde.org/D22567