Bug 106593

StylePropertySet::asText() incorrectly serializes some styles. This causes e.g. document.styleSheets[n].cssRules[m].cssText to generate the wrong CSS text in some cases. I've attached an HTML file which demonstrates one such case. StylePropertySet::asText() is quite complex. It's trying to do clever things with background-position and background-repeat that I do not believe are necessary. Here is a simpler implementation which correctly reserializes a CSSStyleDeclaration. This could be used in PropertySetCSSStyleDeclaration::cssText() in place of the current call to StylePropertySet::asText(). WTF::String SerializeCSSStyleDeclaration(WebCore::CSSStyleDeclaration* decl) { WTF::StringBuilder style_text; WTF::HashSet<WTF::String> emitted_properties; for (int i = 0; i < decl->length(); ++i) { WTF::String name = decl->item(i); if (name.isEmpty()) { continue; } // Now see if this property was part of a shorthand declaration, // e.g. background-image might have been part of a background // shorthand propertly declaration. If there is a shorthand, then // we emit the shorthand property instead if it hasn't already // been emitted. const WTF::String shorthand = decl->getPropertyShorthand(name); if (!shorthand.isEmpty()) { name = shorthand; } if (emitted_properties.contains(name)) { // If we encounter two properties that share the same shorthand, // we only want to emit that shorthand once. continue; } emitted_properties.add(name); const WTF::String value = decl->getPropertyValue(name); if (value.isEmpty()) { continue; } if (!style_text.isEmpty()) { style_text.append(';'); } style_text.append(name); style_text.append(':'); style_text.append(value); const WTF::String priority = decl->getPropertyPriority(name); if (!priority.isEmpty()) { style_text.append(" !"); style_text.append(priority); } } return style_text.toString(); }