remove a stray .gitignore
Add IDL tests for the AudioBuffer interface

Tests generated from the IDL in section 4.9 (The AudioBuffer interface)
of the spec. As we are just testing the interface, the particular
arguments supplied to createBuffer() are inconsequential. We will test
the influence of those arguments in a different test.
Merge pull request #299 from chrislo/submissions/chrislo-audiobuffer-idl-test

Submissions/chrislo audiobuffer idl test