Align the behavior of transform-style: preserve-3d (which allows child elements to participate in the same 3D scene) and the perspective property (which applies a perspective transform to child elements) with the spec by making them apply only to child elements. Before this change, Chromium applies both of these effects based on the containing block hierarchy rather than the DOM tree, and also allows them to extend through elements without transform-related properties on them.
Improve interoperability of CSS 3D transforms, and align with the specification.