src/vs/workbench/services/workingCopy/common/storedFileWorkingCopyManager.ts/StoredFileWorkingCopyManager/onBeforeShutdown
class StoredFileWorkingCopyManager:	private onBeforeShutdown(): boolean {
		if (isWeb) {
			if (this.workingCopies.some(workingCopy => workingCopy.hasState(StoredFileWorkingCopyState.PENDING_SAVE))) {
				// stored file working copies are pending to be saved:
				// veto because web does not support long running shutdown
				return true;
			}
		}

		return false;
	}