Proper non-primitive value replacement for % and replace

[seven-phases-max]

Fixes #2480 as well as similar code with other non-primitive value types.
E.g.:

replace("007", "0", #135); // "#11335507"   / was "undefined07"
replace("007", "0", 2em);  // "2em07"       / was "207"
%("foo-%s", #123);         // "foo-#112233" / was "foo-undefined"
%("bar-%s", 4px);          // "bar-4px"     / was "bar-4"
// etc.

[lukeapage]

looks good will merge manually soon and also do a release before easter..