Make "." a builtin as well

Yeah, it's not going anywhere. This is one line in builtin.cpp vs 9
lines of script, most of which used to print an error that is never triggered.

share/config.fish

@@ -154,16 +154,6 @@ end
 # in UTF-8 (with non-ASCII characters).
 __fish_set_locale
 
-# "." alias for source; deprecated
-function . -d 'Evaluate a file (deprecated, use "source")' --no-scope-shadowing --wraps source
-    if [ (count $argv) -eq 0 ] && isatty 0
-        echo "source: using source via '.' is deprecated, and stdin doesn't work."\n"Did you mean 'source' or './'?" >&2
-        return 1
-    else
-        source $argv
-    end
-end
-
 # Upgrade pre-existing abbreviations from the old "key=value" to the new "key value" syntax.
 # This needs to be in share/config.fish because __fish_config_interactive is called after sourcing
 # config.fish, which might contain abbr calls.

src/builtin.cpp

@@ -342,6 +342,7 @@ int builtin_false(parser_t &parser, io_streams_t &streams, wchar_t **argv) {
 // Functions that are bound to builtin_generic are handled directly by the parser.
 // NOTE: These must be kept in sorted order!
 static const builtin_data_t builtin_datas[] = {
+    {L".", &builtin_source, N_(L"Evaluate contents of file")},
     {L":", &builtin_true, N_(L"Return a successful result")},
     {L"[", &builtin_test, N_(L"Test a condition")},
     {L"and", &builtin_generic, N_(L"Execute command if previous command succeeded")},

tests/checks/complete.fish

@@ -62,7 +62,6 @@ complete
 # CHECK: complete {{.*}}
 # CHECK: complete {{.*}}
 # CHECK: complete {{.*}}
-# CHECK: complete {{.*}}
 
 # Recursive calls to complete (see #3474)
 complete -c complete_test_recurse1 -xa '(echo recursing 1>&2; complete -C"complete_test_recurse1 ")'