getPropertyValue should be case insensitive

Property names retrieved by getPropertyValue, setProperty, removeProperty and others must be treated as case insensitive. This test ensures that they are.

References

• http://bugs.webkit.org/show_bug.cgi?id=14645
• http://www.w3.org/TR/CSS1#forward-compatible-parsing

This paragraph should be green, and not bold when the test completes.