Bad subsequent declaration error

[mhegazy]

The current declaration mismatch error looks like:

error TS2403: Subsequent variable declarations must have the same type.  Variable 'items' has type 'DataTransferItemList' at built/local/lib.d.ts 6521:13, but here has type 'DataTransferItem[]'.

The error was introduced by #19356. I do not think this is the correct solution here. the error as it stands is hard to read, and does not lend itself to navigation..

moreover, it makes our baselines very noisy.

I think the correct solution here is to do revert the changes in #19356 and look into
#10489 instead.