Verifies that CSSStyleSheetHeader.originalContentProvider() indeed returns original content. Running: testSetStyle original content loaded for header: set-style.css == Original == div { color: red; } == Current == div {EDITED: EDITED} Running: testSetSelector original content loaded for header: set-selector.css == Original == div {} == Current == EDITED {} Running: testSetMedia original content loaded for header: set-media.css == Original == @media (all) { } == Current == @media EDITED { } Running: testSetKeyframeKey original content loaded for header: set-keyframe-key.css == Original == @keyframes animation { 100% { color: red; } } == Current == @keyframes animation { from { color: red; } } Running: testAddRule original content loaded for header: add-rule.css == Original == div {} == Current == EDITED {} div {} Running: testSetStyleSheetText original content loaded for header: set-text.css == Original == div {} == Current == EDITED {}