Writing
var o = new <constructor>

after the word "new" the code completion shows everything, even non constructors like Math, JSON, Symbol, Reflect, Intl, SIMD, Atomics, etc. that cannot be used with the new operator.

By the way, could be of great help to have a way to exclude our own static classes from being shown completely after the new operator, e.g. using @static or something like that. If already existing I didn't find it.