Construct the per-element collection and run the mount-time init pass.
Pre-mount user writes (element.foo = …) and pre-mount attribute writes
(setAttribute) leave traces on the element itself — a shadowing data
property and an attribute, respectively — which each ElementProp's
init pass picks up. So there's no separate initialize() step: the
constructor allocates every wrapper and then runs init on each.
The split is internal (allocate-all → init-all) so cascades during init always find existing wrappers in the Map — a wrapper materialized mid-cascade would fire its own default event in addition to the cascading update.
The element this collection belongs to.
Whether propchange dispatch is currently held. While true, writes
append to the burst queue without dispatching; flipping to false
sequentially coalesces undispatched runs (same prop in a row) and
dispatches one event per run.
The class-level prop spec collection.
Propagate an observed attribute change to every prop reflected from it.
Attribute name.
OptionaloldValue: stringGet the ElementProp wrapper for a prop by name, creating it on demand from this element's own class-level Props.
Either dispatch a propchange synchronously or queue it for resume,
then cascade updates to any dependents.
The prop that changed.
Change descriptor (see ElementProp#set).
Per-element collection of ElementProp wrappers.