Emit tab characters as \9 (#104)

Closes #103

Author: nex3

doc-src/SASS_CHANGELOG.md

@@ -3,6 +3,11 @@
 * Table of contents
 {:toc}
 
+## 3.7.3 (Unreleased)
+
+* Emit escaped tab characters in identifiers as `\9` rather than a backslash
+  followed by a literal tab.
+
 ## 3.7.2 (8 November 2018)
 
 * Fix more escaped-whitespace edge cases.

lib/sass/util.rb

@@ -269,7 +269,7 @@ def normalize_ident_escapes(ident, start: true)
         at_start = start && $1
         char = escaped_char(s)
         next char if char =~ (at_start ? Sass::SCSS::RX::NMSTART : Sass::SCSS::RX::NMCHAR)
-        if char =~ (at_start ? /[\x0-\x8\xA-\x1F\x7F0-9]/ : /[\x0-\x8\xA-\x1F\x7F]/)
+        if char =~ (at_start ? /[\x0-\x1F\x7F0-9]/ : /[\x0-\x1F\x7F]/)
           "\\#{char.ord.to_s(16)} "
         else
           "\\#{char}"

test/sass/engine_test.rb

@@ -3325,7 +3325,7 @@ def test_numeric_formatting_of_integers
 
   def test_escaped_semicolons_are_not_compressed
     assert_equal(<<'CSS', render(<<'SASS', :syntax => :scss, :style => :compressed))
-div{color:#f00000\	\0 \;}
+div{color:#f00000\9 \0 \;}
 CSS
 div {
  color: #f00000\9\0\;