ScrollbarStyles contains values of overflow, (over)scroll-behavior, etc.
The only one which is marginally related to scroll _bars_ is overflow, which can
be used to hide scrollbar (by making an element not scrollable) or enforce the
scrollbar to display.
It makes more sense to be called ScrollStyles as it's mainly concerning behavior
of scrolling, not scrollbars. Also, with the addition of scrollbar width
properties, the current name can be confusing.
Overflow properties have two purposes:
1. controlling whether the scrollbar should be shown;
2. controlling whether the content is scrollable.
However, with the scrollbar-width property being added, scrollability and
presence of a scrollbar are no longer tied together.
This patch makes a separation between the value of overflow and the presence of
a scrollbar by making it clear that for ScrollReflowInput, we only care about
whether scrollbar should be shown.
This should make it easier to write the logic involving presence of the
scrollbar based on webdev choice.
Part 1: Remove current table item, as it's never set.
Part 2: Get rid of generic table painting code, and handle each class separately.
Part 4: Hoist outline skipping into col(group) frame code.
Part 5: Skip box-shadow for table column and column groups.
Part 6: Store column and column group backgrounds separately, and then append them before the rest of the table contents.
Part 7: Pass rects in display list coordinates to AppendBackgroundItemsToTop.
Part 8: Create column and column group background display items as part of the cell's BuildDisplayList.
Part 9: Used cached values instead of calling nsDisplayListBuilder::ToReferenceFrame when possible, since it can be expensive when the requested frame isn't the builder's current frame.
Part 10: Make sure we build display items for table parts where only the normal position is visible, since we may need to create background items for ancestors at that position.
Part 11: Create an AutoBuildingDisplayList when we create background items for table columns and column groups, so that we initialize the invalidation state correctly.
Moonchild
win7-7
wolfbeast
wolfbeast
Matt A. Tobin