This test setting various attributes of a CSSOM elements to JavaScript null.

TEST SUCCEEDED: The value was the string '.foo { color: black; }'. [tested CSSRule.cssText]

TEST SUCCEEDED: The value was the string '.foo'. [tested CSSStyleRule.selectorText]

TEST SUCCEEDED: The value was the empty string. [tested CSSStyleDeclaration.cssText]

TEST SUCCEEDED: The value was the string 'black'. [tested CSSValue.cssText]

TEST SUCCEEDED: The value was the empty string. [tested MediaList.mediaText]