Vertical metrics tests

Please see VerticalMetricsRecommendatations on the googlewebfonts wiki for more information about the tests here.

Tests in this directory include:

• test.html - many copies of a webfont, each with a different tweak to vertical metrics, to see how different browsers behave.
• test2.html - more specific tests to see how browsers deal with double-stacked accents in both web and system fonts.
• test3.html - same as test.html but with line-height set explicitly to 1.2.
• screenshots.html - screenshots of test.html taken with ten or so popular browsers.