Fix: variable names beginning with a keyword and dash

lib/lexer.js

@@ -448,7 +448,7 @@ Lexer.prototype = {
   keyword: function() {
     var captures
       , tok;
-    if (captures = /^(return|if|else|unless|for|in)\b[ \t]*/.exec(this.str)) {
+    if (captures = /^(return|if|else|unless|for|in)\b(?!-)[ \t]*/.exec(this.str)) {
       var keyword = captures[1];
       this.skip(captures);
       if (this.isPartOfSelector()) {

test/cases/regression.2422.css

@@ -0,0 +1,13 @@
+.foobar {
+  border-radius: 4px;
+  columns: 5;
+  foo: 1;
+  foo: 2;
+  foo: 3;
+}
+@media (min-width: 600px) {
+  .foobar {
+    columns: 1;
+    font-weight: 700;
+  }
+}

test/cases/regression.2422.styl

@@ -0,0 +1,18 @@
+forsooth = 4px
+for-something = 5
+if_bar = 700
+
+for-tablet-portrait-up()
+  @media (min-width: 600px)
+    {block}
+
+.foobar
+  border-radius: forsooth
+  columns: for-something
+
+  for --num in 1 2 3
+    foo: --num
+
+  +for-tablet-portrait-up()
+    columns: 1
+    font-weight: if_bar