The old style of merging all of a function's variable declarations into
a single statement made some sense back in the days of var, but there's
no reason to keep doing it now that we use const and let.
The original asymmetric matcher code for Any did not work with symbols
since `symbolInstance instanceof Symbol` is actually `false` (but,
`symbolInstance.constructor` is `Symbol). This simply adds an extra
clause that explicitly checks for symbol (if available) like the other
primitive types.
Also added some missing specs for other types, like Map, Set, etc.
Fixes#1431.
