Revert "add elixirGuardFunction syntax for functions that are supported in"

This reverts commit db32e4b.

Author: jbodah

spec/syntax/guard_spec.rb

@@ -18,27 +18,27 @@
 
 describe 'Guard syntax' do
   it 'guard in function' do
-    expect(<<~EOF).to include_elixir_syntax('elixirGuardFunction', 'is_atom')
+    expect(<<~EOF).to include_elixir_syntax('elixirKeyword', 'is_atom')
     def fun(a) when is_atom(a), do:
     EOF
   end
 
   it 'guard in if' do
-    expect(<<~EOF).to include_elixir_syntax('elixirGuardFunction', 'is_atom')
+    expect(<<~EOF).to include_elixir_syntax('elixirKeyword', 'is_atom')
     if is_atom(:atom), do: true
     EOF
   end
 
   it 'guard in case' do
-    expect(<<~EOF).to include_elixir_syntax('elixirGuardFunction', 'is_atom')
+    expect(<<~EOF).to include_elixir_syntax('elixirKeyword', 'is_atom')
     case true do
       true when is_atom(:atom) -> true
     end
     EOF
   end
 
   it 'guard in case (multiline)' do
-    expect(<<~EOF).to include_elixir_syntax('elixirGuardFunction', 'is_atom')
+    expect(<<~EOF).to include_elixir_syntax('elixirKeyword', 'is_atom')
     case true do
       true when is_boolean(true) and
       is_atom(:atom) -> true

syntax/elixir.vim

@@ -20,8 +20,6 @@ syn match elixirId '\<[_a-zA-Z]\w*[!?]\?\>' contains=elixirUnusedVariable
 
 syn match elixirKeyword '\(\.\)\@<!\<\(for\|case\|when\|with\|cond\|if\|unless\|try\|receive\|after\|rescue\|catch\|else\|quote\|unquote\|super\|unquote_splicing\)\>:\@!'
 
-syn match elixirGuardFunction '\(\.\)\@<!\<\(is_atom\|is_binary\|is_bitstring\|is_boolean\|is_float\|is_function\|is_integer\|is_list\|is_map\|is_nil\|is_number\|is_pid\|is_port\|is_reference\|is_tuple\|abs\|binary_part\|bit_size\|byte_size\|div\|elem\|hd\|length\|map_size\|node\|rem\|round\|self\|tl\|trunc\|tuple_size\|band\|bor\|bnot\|bsl\|bsr\|bxor\)\>:\@!'
-
 syn keyword elixirInclude import require alias use
 
 syn keyword elixirSelf self