unzip is missing from documentation and is required to run 
"gclient sync"  successfully. Unzip does not come installed by default
on every Linux installations.
Signed-off-by: NPhilippe Ombredanne <pombredanne@nexb.com>

* Rename hittable to hitTestable

Apparently hittable is not politically correct.

* Enable tracing on Fuchsia

Apparently hittable is not politically correct.

Also, change the hit testing geometry so that we get our hits at the root.

This will ensure the flx file is rebuilt whenever the manifest is modified.

* Update Skia revision to pull in GL native interface construction fixes on iOS.

Fixed in https://skia-review.googlesource.com/c/5212/

* Use the new image encoder API from Skia.

There's no reason to present offscreen child views to Mozart.

This interface has been replaced with HandleWaiter, which is the new hotness.

The same will be removed from buildroot as well.

- [x] Use Dart_GetLoadedLibraries which is available in product builds.

This file is identical (to the byte) to the LICENSE file in the same directory, and no file in this directory refers to it.

This requires an updated buildroot.

We need to compute the paint bounds of ChildViewLayers during Preroll.
Also, we need to allocate a BlendPtr before writing into it.

This also removes a reference to mojo_gni.

We push a bit up the tree during preroll to learn whether there system
composited layers below each layer. During update scene, we squash down
to paint tasks, which we execute after publishing the new scene.

* The lastchange hook wrote a file no one ever read.
* We don’t need binutils because we don’t use debug fission on Linux.
* We dont use eu-strip.