This reverts commit a974b781.

Co-authored-by: NKaushik Iska <kaushikiska@google.com>

This enables proper compositing of surfaces with elevation over
a PlatformViewLayer.
Co-authored-by: NSanjay Chouksey <sanjayc@google.com>

* first batch of @js bindings

The dart SDK needs to ship several packages which have opted into null safety for the tech preview. This requires the use of a package_config.json for compilation as this file contains the language versions. Use a dart script to generate the package_config file from the .packages file, and include that in the DEPS hooks section.

Fixes flutter/flutter#60628

* use Object for operator==

* apply style guide for operator==