We currently test if font description has changed to see if all properties need to be applied. However only a few size related metrics can actually affect other properties. We can just test those, making the cache somewhat more effective while also making the test faster.
Created attachment 112694 [details] patch
http://trac.webkit.org/changeset/98803
It made all tests assert on Qt in debug mode: ASSERTION FAILED: fontCache()->generation() == m_generation ../../../Source/WebCore/platform/graphics/FontFallbackList.cpp(104) : const WebCore::FontData* WebCore::FontFallbackList::fontDataAt(const WebCore::Font*, unsigned int) const Could you check it, please?
It appears that this patch broke 500+ tests on Windows: http://build.webkit.org/builders/Windows%207%20Release%20%28Tests%29/builds/17418
Rolled out in http://trac.webkit.org/changeset/98826, don't know yet why this would fail only on some platforms.
Attachment 112694 [details] was posted by a committer and has review+, assigning to Antti Koivisto for commit.
This path doesn't seem relevant after the updated CSS parser.
<rdar://problem/98005179>