patch 8.2.2160: various typos

Problem:    Various typos.
Solution:   Fix spelling mistakes. (closes #7494)
diff --git a/src/testdir/test_debugger.vim b/src/testdir/test_debugger.vim
index b363640..029b9db 100644
--- a/src/testdir/test_debugger.vim
+++ b/src/testdir/test_debugger.vim
@@ -974,7 +974,7 @@
         \ 'line 1: let s:file1_var = ''file1'''
         \ ], #{msec: 5000})
 
-  " step throught the initial declarations
+  " step through the initial declarations
   call RunDbgCmd(buf, 'step', [ 'line 2: let g:global_var = ''global''' ] )
   call RunDbgCmd(buf, 'step', [ 'line 4: func s:File1Func( arg )' ] )
   call RunDbgCmd(buf, 'echo s:file1_var', [ 'file1' ] )