[webkit-dev] Back/forward cache for pages with unload handlers

[Brady Eidson]

Since the beginning, WebKit has excluded pages with unload handlers  
from its back/forward cache.  There has been an unspoken assumption  
for 6 years now that we "have to do it."

In recent explorations to improvements we can make to the back/forward  
cache, we've collected tons of data that suggests:
-It would be a huge win for end users to remove this restriction, as  
many pages are excluded from the page cache because they have unload  
handlers.
-Many are designed to do the same work in the pagehide handler under  
Firefox.
-Many of these unload handlers don't do anything actually important.

In our quest to make WebKit better for end users, we'd like to explore  
removing this limitation.  We would like to encourage developers to  
use pagehide in WebKit now that we support it, and we won't know if  
anything truly important breaks until we try it.  I intend to land a  
patch removing the restriction sometime tomorrow.

If anyone needs to keep it working for their port, please comment in  
the bugzilla before then, as I don't mind one bit #ifdef'ing it so it  
only affects the main Mac/Windows ports:
https://bugs.webkit.org/show_bug.cgi?id=29021

Thanks,
~Brady