Added debugger and VM service to VMGlue.
Added gl.dart as builtin resource.
Trying to get some more samples to work.

Added GetFileAsString to extension.
Added a couple more classes and methods to gl.dart.
Set window's innerWidth and innerHeight with the surface's values.
Refactoring in progress

Added dart:web_gl and dart:web_audio
Load assets using Asset Manager (no more copying assets around)
Added some more webgl methods and constants
Store Dart function pointers for our callbacks