Make VimL code compatible with merged Partial support (#5765)

Closes #5763.

runtime/autoload/health/provider.vim

@@ -25,7 +25,7 @@ function! s:version_cmp(a, b) abort
 endfunction
 
 " Handler for s:system() function.
-function! s:system_handler(jobid, data, event) abort
+function! s:system_handler(jobid, data, event) dict abort
   if a:event == 'stdout' || a:event == 'stderr'
     let self.output .= join(a:data, '')
   elseif a:event == 'exit'

runtime/autoload/vimexpect.vim

@@ -140,7 +140,7 @@ endfunction
 
 
 " Job handler that simply forwards lines to the parser.
-function! s:JobOutput(id, lines)
+function! s:JobOutput(_id, lines, _event) dict
   call self._parser.feed(a:lines)
 endfunction
 

test/functional/core/job_spec.lua

@@ -368,11 +368,11 @@ describe('jobs', function()
       eq({'notification', 'wait', {{-2}}}, next_msg())
     end)
 
-    pending('can be called recursively', function()
+    it('can be called recursively', function()
       source([[
       let g:opts = {}
       let g:counter = 0
-      function g:opts.on_stdout(id, msg)
+      function g:opts.on_stdout(id, msg, _event)
         if self.state == 0
           if self.counter < 10
             call Run()
@@ -390,7 +390,7 @@ describe('jobs', function()
           call jobclose(a:id, 'stdin')
         endif
       endfunction
-      function g:opts.on_exit()
+      function g:opts.on_exit(...)
         call rpcnotify(g:channel, 'w', printf('job %d exited', self.counter))
       endfunction
       function Run()