[mathml-tests] Import tests for MathML lengths. (#4008)

These tests pass on Gecko but some of them are failing on WebKit because of some bugs in the MathML implementation.

@karlt Can you please review these tests, so that we can import them into Mozilla test suite?

View on GitHub: https://github.com/w3c/web-platform-tests/pull/4008

Received on Tuesday, 18 October 2016 16:09:35 UTC