Bug 126177

Summary: REGRESSION(r133214): Don't invalidate style when adding classes that don't match rules
Product: WebKit Reporter: Ryosuke Niwa <rniwa>
Component: CSSAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal CC: cmarcelo, commit-queue, esprehn+autocc, kangil.han, kling, koivisto
Priority: P2 Keywords: BlinkMergeCandidate
Version: 528+ (Nightly build)   
Hardware: Unspecified   
OS: Unspecified   
Attachments:
Description Flags
patch andersca: review+

Description Ryosuke Niwa 2013-12-23 12:53:27 PST 
Consider merging https://chromium.googlesource.com/chromium/blink/+/50ffb9fad31542e86de85e3305894d99b1d81d34
or come up with a better fix if the regression exists in WebKit.

r133214 caused a regression by making us mark elements for style recalc
when adding new classes that don't match any rules due to a logic error
in checkSelectorForClassChange. This patch corrects the logic error so
that now adding and removing class names that don't match rules will
not trigger a style recalc.

To facilitate testing this patch I added a new Internals API:
updateStyleAndReturnAffectedElementCount(). It updates the style of the document
and returns the number of elements that had a style computed for them. This
will also allow writing future tests when we make things smarter to avoid
recalcs.
Comment 1 Antti Koivisto 2014-01-27 08:42:52 PST 
Created attachment 222328 [details]
patch
Comment 2 Antti Koivisto 2014-01-27 09:08:39 PST 
https://trac.webkit.org/r162843