For anyone who watches Fox News Channel, it's not at all surprising that its anchors and hosts (with few notable exceptions) talk up President Donald Trump while knocking down the Democrats running against him in 2020. While that position puts Fox somewhere in the gray area between journalism and activism, it's not exactly new. There are ratings in partisanship -- so Fox News engages in partisanship. But even partisanship should have its limits. And one of those limits should be raising entirely unfounded questions about a presidential candidate's health. Which is exactly what two Fox News personalities -- Kennedy and...