Version 3.0.0 of Phaser is still in active development. It might blow stuff up.
Phaser is publicly developed on the dev branch of our github repository.
This is where bug fixes are applied and new features are tested. So consider it 'bleeding edge'. It's certainly not guaranteed to always work.
Don't forget: When you clone the repository, make sure you switch to the dev branch to access the latest version.
Build from Source
It's important to understand that we very rarely push new build files to the dev branch. For that reason you should always clone the whole repository and use the provided grunt scripts to build your own phaser.js files for testing.
Please keep this in mind should we close your issue with "fixed in dev" or a similar message. It means we've fixed the issue in the source code itself, but that change isn't necessarily yet in the build files.
From Dev to Master
We build the new release of Phaser in the dev branch. And when we're ready we merge it to master and tag it.
Because of this process if you submit a Pull Request you should always do it against the dev branch. You can find out more details in our Contributors Guide.