vim-patch:8.2.1241: cannot use getbufinfo() as a method

Problem:    Cannot use getbufinfo() as a method.
Solution:   Support using getbufinfo() as a method. (closes vim/vim#6458)
6434fc574d

runtime/doc/eval.txt

@@ -4701,7 +4701,9 @@ getbufinfo([{dict}])
 <
 		To get buffer-local options use: >
 			getbufvar({bufnr}, '&option_name')
-
+<
+		Can also be used as a |method|: >
+			GetBufnr()->getbufinfo()
 <
 							*getbufline()*
 getbufline({buf}, {lnum} [, {end}])

src/nvim/eval.lua

@@ -137,7 +137,7 @@ return {
     ['function']={args={1, 3}, base=1},
     garbagecollect={args={0, 1}},
     get={args={2, 3}, base=1},
-    getbufinfo={args={0, 1}},
+    getbufinfo={args={0, 1}, base=1},
     getbufline={args={2, 3}, base=1},
     getbufvar={args={2, 3}, base=1},
     getchangelist={args={0, 1}, base=1},

src/nvim/testdir/test_bufwintabinfo.vim

@@ -20,6 +20,9 @@ function Test_getbufwintabinfo()
   call assert_equal('vim', l[0].variables.editor)
   call assert_notequal(-1, index(l[0].windows, '%'->bufwinid()))
 
+  let l = '%'->getbufinfo()
+  call assert_equal(bufnr('%'), l[0].bufnr)
+
   " Test for getbufinfo() with 'bufmodified'
   call assert_equal(0, len(getbufinfo({'bufmodified' : 1})))
   call setbufline('Xtestfile1', 1, ["Line1"])