Add missing data members in StyleRareNonInheritedData copy constructor.

Two data members are missing from the StyleRareNonInheritedData copy
constructor. This can be problematic because StyleRareNonInheritedData
is stored with copy-on-write semantics: when two ComputedStyles share
the same StyleRareNonInheritedData, modifying one of them will create
a copy without copying those two data members.

This patch adds callback_selectors and paint_images into the copy
constructor.

BUG=628043

Review-Url: https://codereview.chromium.org/2893243002
Cr-Commit-Position: refs/heads/master@{#476577}
1 file changed