Backed out 3 changesets (bug 977126) for mochitest-2 bustage on Windows

Backed out changeset 2daa537b62e6 (bug 977126)
Backed out changeset d87a13b71afc (bug 977126)
Backed out changeset 3bd335914852 (bug 977126)
Backed out changeset 533e61eb95d3 (bug 991234) for mochitest-2 bustage on Windows