Microsoft submissions for Test Assertions 12.1, 7.5, 7.6, and 7.7

Hi folks,

I've submitted a new pull request adding in tests for 12.1, 7.5, 7.5, and 7.7 authored by Artem [1].  I've updated the test assertions list to reflect this submission also [2]. We'd appreciate your review as soon as possible so we can get to 100% coverage.

Thanks!

-Jacob

[1] https://github.com/w3c/web-platform-tests/pull/1074
[2] http://www.w3.org/wiki/PointerEvents/TestAssertions