Undo/redo in unlink test.
Better name for non-IE exec-toggle tests.
Better handling of undesirable spans created by execCommand
Make jshint happy.
More Unlink tests.
Missing semicolon.
_exec: remove classless spans only if they have font-weight: normal;
Some more unlink tests.
Merge pull request #632 from wymeditor/exec-manipulations

Improve `_exec` and its test coverage
Merge branch 'master' into issue_512
Test undo/redo in some new link/unlink tests.
Remove extra comma.