regression: SingleLineTestResult cuts off test result printing

[juj]

The PR that changed test runner to use the single line test result printer caused a problem that test output is cut off at the end.

Noticed this when adding #25835:

Above screenshot shows Command Prompt window on top a browser window.

the line should print skipped 'This test requires a browser with ES6 Module Workers support'

[sbc100]

It should indeed be truncate, but it should happen at the terminal width.. not in the middle like that. I'll take a look.