HTMLConverter::aggregatedAttributesForAncestors should cache intermediate results

HTMLConverter::aggregatedAttributesForAncestors should cache intermediate results
https://bugs.webkit.org/show_bug.cgi?id=131400

Reviewed by Sam Weinig.

Instead of accumulating attributes from a character node to the highest ancestor,
recursively call aggregatedAttributesForElementAndItsAncestors so that aggregated
attributes are cached on each ancestor to eliminate the old O(n^2) behavior.

* editing/cocoa/HTMLConverter.mm:
(HTMLConverter::aggregatedAttributesForAncestors):
(HTMLConverter::aggregatedAttributesForElementAndItsAncestors): Extracted from aggregatedAttributesForAncestors.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@166981 268f45cc-cd09-0410-ab3c-d52691b4dbfc