DevTools occasionally freezes when using WASM

I've managed to rather reliably get DevTools to freeze when compliling to WASM.

Steps to repro:
- Run devtools with `devtools_tool serve --wasm --no-strip-wasm`
- Enable the WASM setting (in the settings dialog), and wait for window to reload
- Navigate to the Debugger panel, and click on the file name to open the file picker
- Click another file name in the dropdown to open that file
- Repeat a few times (rather quickly), eventually DevTools will freeze