vim-patch:8.1.1911: more functions can be used as methods

Problem:    More functions can be used as methods.
Solution:   Make a few more functions usable as a method.
64b4d73524

Note that the old-style version of Test_byteidx() was already translated
to a Lua test in 069_multibyte_formatting_spec.lua. Keep both versions,
using Test_byteidx() to mainly test the method call syntax for byteidx()
and byteidxcomp().

src/nvim/eval.lua

@@ -62,10 +62,10 @@ return {
     bufnr={args={0, 2}, base=1},
     bufwinid={args=1, base=1},
     bufwinnr={args=1, base=1},
-    byte2line={args=1},
-    byteidx={args=2},
-    byteidxcomp={args=2},
-    call={args={2, 3}},
+    byte2line={args=1, base=1},
+    byteidx={args=2, base=1},
+    byteidxcomp={args=2, base=1},
+    call={args={2, 3}, base=1},
     ceil={args=1, base=1, func="float_op_wrapper", data="&ceil"},
     changenr={},
     chanclose={args={1, 2}},