Improve performance of HTMLSelectElement::m_listItems update.
This CL introduces a fast path to update m_listItems directly instead of throwing
it away and reconstructing it. The fast path supports:
- Prepend an OPTION to a SELECT element
- Append an OPTION to a SELECT element
- Remove an OPTION child from a SELECT element or an OPTGROUP element.
Removing 20,000 OPTIONs: 2,813ms -> 200ms
BUG=620142, 624220
Review-Url: https://codereview.chromium.org/2110303002
Cr-Commit-Position: refs/heads/master@{#403093}
2 files changed
