JavaFX 11 on Android

[Johan Vos]

Hi,

I worked from the openjfx/develop repository and created a version that
works on Android (will work on iOS soon).
This required some changes, as we're running on top of the Android VM,
which is not really Java (not even close).
The longer-term goal is to run a JVM on Android as well, but that is not
something to discuss in this topic.

The changes I had to make are in this diff:
https://github.com/javafxports/openjdk-jfx/compare/develop...johanvos:android

There are a number of changes:

1. Changes in the Android specific files (e.g. FXDalvikEntity): those are
mainly changes we did in the 8-tree, but that were never sent upstream. I
think most of those can be upstreamed (after cleanup and review of course)

2. Changes in Monocle, mainly related to scale factor and HiDPI. Those can
probably be upstreamed as well

3. Changes in the buildSrc/dalvik.gradle. Those are android-only, so can be
upstreamed too.

4. Changes in common java classes (e.g. no System.Logger). Those are a
problem.

While I am in favour of leveraging the latest version of Java for doing
JavaFX development, I do realise this breaks the Android port (not the iOS
port, as we use a VM based on OpenJDK already there).
While in theory we could deal with this using reflection (and this has been
done in the 8-tree, e.g. for isIdeographic()), I don't think this is a good
idea.

My proposal would therefore be that I split the changes into
Android/Dalvik/Monocle changes that do not affect any other platform, and
create PR's for merging these changes in upstream. While my prototype is
working (see https://twitter.com/johanvos/status/1047804607320260608)  I
need to clean up the patches, and I suggest I create smaller PR's that are
easier to digest.

For the changes in the common classes, I think it's best to use a fork, or
to patch the system at build time -- rather than polluting the main
repository with reflection-based checks.

Thoughts?

- Johan