Follow-up to bug 1404181.

With retained display lists, we keep a list of frames that have been modified between the paints. If this list contains certain types of frames such as canvas (large display port area) or scrollbar frames (different async AGR), we almost certainly end up rebuilding the whole display list again. This combined with display list preprocessing and merging overhead will make us slower than just doing a full rebuild. Hopefully we can address these cases later. This patch also adds a pref that can be used to set the upper bound for modified frames before a full rebuild is done. The default value 500 was selected based on empirical testing (Amazon/Facebook/Youtube on MBP).

Comment on attachment 8921455 [details] Bug 1411248 - Add some early exit heuristics to avoid complicated partial display list builds https://reviewboard.mozilla.org/r/192500/#review197734

We're sorry, Autoland could not rebase your commits for you automatically. Please manually rebase your commits and try again. hg error in cmd: hg rebase -s 29ae88c75c65 -d cb757b237396: rebasing 429444:29ae88c75c65 "Bug 1411248 - Add some early exit heuristics to avoid complicated partial display list builds r=mattwoodrow" (tip) merging gfx/thebes/gfxPrefs.h merging modules/libpref/init/all.js warning: conflicts while merging gfx/thebes/gfxPrefs.h! (edit, then use 'hg resolve --mark') unresolved conflicts (see hg resolve, then hg rebase --continue)

Pushed by mikokm@gmail.com: https://hg.mozilla.org/integration/autoland/rev/2ecebc7f1475 Add some early exit heuristics to avoid complicated partial display list builds r=mattwoodrow