SELECT element: Avoid to use listItems() in HTMLSelectElement::selectOption()
Remove listItems() usage from:
- HTMLOptionElement::index()
- HTMLSelectElement::saveListboxActiveSelection()
- HTMLSelectElement::selectedOption()
- HTMLSelectElement::deselectItemsWithoutValidation()
We use optionList() instead.
These changes don't improve computational complexity. However we can avoid to
update m_listItems when we add/remove OPTIONs.
Other changes:
- HTMLSelectElement::updateListBoxSelectioN() needs to be updated to synchronize
with saveListboxActiveSelection(). m_cachedStateForActiveSelection now
represents OPTIONs instead of listItems, which includes OPTGROUP and HR.
- Change the arguments of OptionList and OptionListIterator to |const| so that
we can create them in const member functions of HTMLSelectElement.
- Remove the optimized fast path in HTMLSelectElement::setRecalcListItems(). We
don't use m_listItems in critical paths any longer. So the optimization isn't
necessary.
This CL improves performance because of the removal of the fast path.
blink_perf.dom:
select-multiple-add: 1,772 runs/s -> 1,912 runs/s
select-single-add: 867.9 runs/s -> 944.7 runs/s
select-single-remove: 137.9 runs/s -> 145.5 runs/.s
BUG=577989
Review-Url: https://codereview.chromium.org/2131073002
Cr-Commit-Position: refs/heads/master@{#404591}
5 files changed
