The basic idea here is as follows:
* Rule nodes are reference-counted, but releasing them adds them to a linked
list rather than freeing them. This allows for the reuse that motivated the
original GC scheme.
* We get rid of the marking, and instead rely on the reference count.
* Sweeping no longer requires a complicated traversal. We just pop items
off the free list until it's empty. When a child is destroyed, its parent
may go onto the free list.
* We remove special handling for the root node, and use a regular reference-counted
edge from the style set.
* The free list automatically asserts that it's empty (meaning all nodes have been
freed) in its destructor, which runs when the style set is destroyed.
* We get rid of the list of style context roots on the style set. We still need
a count though, because of the HasCachedStyleData check.
These new enum values are added with same behavior as their modern flexbox
equivalents -- they're hooked up to NS_NewFlexContainerFrame, and they're
listed alongside the modern flexbox enums in 'switch' & 'if' statements.
There's one exception, which I call out with a comment at the end of the patch:
we don't treat -webkit-box the same as flexbox in IsFlexOrGridDisplayType(),
because that method is used to determine whether we should blockify
inline-level children of a flex/grid container, and we don't want to blockify
any children of a -webkit-box. (Instead, we want to wrap them in an anonymous
flex item. That happens in the next patch.)
MozReview-Commit-ID: 9BB4Ib2KpvE
This adds the value -moz-window-dragging: default as the initial value of the property,
and makes it a [reset] property. This allows us to change the way the window dragging
region is calculated: Elements with -moz-window-dragging: no-drag will now always be
undraggable, even if they are overlapped by -moz-window-dragging: drag elements. That
way we can keep the region calculation simple and don't have to add code to respect
z-ordering.
Without the code change, the property_database.js changes lead to:
* 3 failures in test_value_cloning.html (one each for
transition-property, -moz-transition-property, and
-webkit-transition-property) that "computed value should be nonempty"
* 6 failures in test_value_computation.html (two each for
*transition-property) that "should not get empty value"
* 16 failures in test_value_storage.html "parse+compute+serialize...
should be idempotent": 2 for each longhand, 2 for the shorthand for
the unprefixed, and 4 for the shorthand for each prefixed
The casts in nsCSSProps.cpp (defining kBoxSizingKTable) and in
nsComputedDOMStyle::DoGetBoxSizing (using
nsCSSProps::ValueToKeywordEnum) are a little bit annoying, though aren't
a net reduction in typesafety.
The casts in nsRuleNode.cpp (SetDiscrete) are a little more annoying,
though the change in this patch should be sufficient for converting all
properties -- but that may also mean reducing typesafety a bit for all
properties.
I'd like to find something better to do about them, but I think I'm ok
landing this before doing that. Bug 1224918 covers doing better.
