Summary:
Some recent change to Chrome causes the remote debugger to be throttled unexpectedly if it is in a background tab. Although this does not fix the problem, it raises the issue and suggests a workaround.
I also cleaned up some littering of the global namespace in the debugger web worker.
Reviewed By: jingc
Differential Revision: D4104515
fbshipit-source-id: 56e46c0e759bec4c42d3baedd4d2d46cdea2e4a0