[audioworklet] Moving AudioContextInfo to AudioWorkletGlobalScope

[hoch]

Currently AudioContextInfo is located at AudioWorkletProcessor, but it seems wasteful considering sampleRate and currentTime are identical to all instances in an AudioWorkletGlobalScope.

So I am proposing moving individual attributes of AudioContextInfo to AudioWorkletGlobalScope:

interface AudioWorkletGlobalScope : WorkletGlobalScope {
  void registerProcessor (DOMString name, VoidFunction processorCtor);
  readonly attribute double currentTime;
  readonly attribute float sampleRate;
}

Calling AudioContextInfo() creates a dictionary, so accessing the primitive values directly should be more efficient and less wasteful. (in terms of GC)

[joeberkovitz]

When fixing this, be sure to update the code examples.