HTMLOptionElement.prototype.selected setter should not make an option dirty if it doesn't change its selectedness and the option is owned by a select element.
We implmeneted option dirtiness in [1] and it conformed to the standard.
However, it was not compatible with other browsers and caused a regression.
This CL makes the dirtiness behavior compatible with Firefox.
[1] crrev.com/363172
BUG=570367
TEST=automated
Review URL: https://codereview.chromium.org/1541753002
Cr-Commit-Position: refs/heads/master@{#366784}
2 files changed
