Test for CSS.styleSheetAdded and CSS.styleSheetRemoved events. == Running test suite: CSS.StyleSheetEvents.Basic -- Running test case: CheckNoStyleSheets PASS: Should be no stylesheets. -- Running test case: AddStyleTag PASS: StyleSheetAdded event should fire. -- Running test case: DisableStyleTag PASS: StyleSheetRemoved event should fire for the same CSSStyleSheet. -- Running test case: EnableStyleTag PASS: StyleSheetAdded event should fire with a new CSSStyleSheet. -- Running test case: RemoveStyleTag PASS: StyleSheetAdded event should fire. -- Running test case: AddExternalStyleSheet PASS: StyleSheetAdded event should fire. Added StyleSheet with URL: inspector/css/resources/external.css -- Running test case: DisableExternalStyleSheet PASS: StyleSheetRemoved event should fire for the same CSSStyleSheet. -- Running test case: EnableExternalStyleSheet PASS: StyleSheetAdded event should fire with a new CSSStyleSheet. -- Running test case: DisableExternalStyleSheetViaMediaAttribute PASS: StyleSheetRemoved event should fire for the same CSSStyleSheet. -- Running test case: EnableExternalStyleSheetViaMediaAttribute PASS: StyleSheetAdded event should fire with a new CSSStyleSheet. -- Running test case: RemoveExternalStyleSheet PASS: StyleSheetAdded event should fire. Removed StyleSheet with URL: inspector/css/resources/external.css