clean up import paths

[nicksnyder]

These paths caused me problems when I was trying to pursue method 1 in microsoft/vscode#20623

When running ./scripts/code.sh in vscode I saw:

[85253:0214/175725:INFO:CONSOLE(84)] "Activating extension `lukehoban.vscode-go` failed: Cannot find module '../src/diffUtils'.", source: file:////Users/nick/code/vscode/out/vs/workbench/services/message/browser/messageService.js (84)

Seems like these paths are otherwise equivalent so I hope this doesn't cause a problem elsewhere.

[msftclas]

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