We currently cache and share parsed data structures of stylesheets loaded with <link>. We should do the same with stylesheets loaded using @import rules as they are also fairly common.
Created attachment 161018 [details] patch Mutation-of-shared-import case could probably use a test case. Not sure if that is covered.
Comment on attachment 161018 [details] patch View in context: https://bugs.webkit.org/attachment.cgi?id=161018&action=review Awesome. r=me > Source/WebCore/css/StyleRuleImport.cpp:62 > -void StyleRuleImport::setCSSStyleSheet(const String& url, const KURL& baseURL, const String& charset, const CachedCSSStyleSheet*) > +void StyleRuleImport::setCSSStyleSheet(const String& url, const KURL& baseURL, const String& charset, const CachedCSSStyleSheet* ) ORLY?
http://trac.webkit.org/changeset/127123 Turned out we have test coverage for import mutations too.
Rolled out in <http://trac.webkit.org/changeset/128637>, because this depended on an earlier patch that had to be rolled out.