Doc comments for a param on the same line as the function name show as a comment for the function itself

[sean-mcmanus]

Repros with 1.29.0 with

class Afterdoc_Test
{
    void sum(int one, // first param,
        int two // second param
    ); // computes the sum
};

Doc comment shows "first param" for the comment of sum.

Regression for the 2nd bug fix of #13725 . However, that bug seems higher priority than this bug, which is why we haven't reverted that fix.