Fixes parse error with blank attributes

Fixes zmoazeni#6

Author: zmoazeni

lib/csscss/parser/css.rb

@@ -20,6 +20,8 @@ class Parser < Parslet::Parser
           comment.repeat(1) | space?
         }
 
+        rule(:blank_attribute) { str(";") >> space? }
+
         rule(:attribute) {
           match["^:{}"].repeat(1).as(:property) >>
           str(":") >>
@@ -33,7 +35,7 @@ class Parser < Parslet::Parser
             match["^{}"].repeat(1).as(:selector) >>
             str("{") >>
             space? >>
-            (comment | attribute).repeat(0).as(:properties) >>
+            (comment | attribute | blank_attribute).repeat(0).as(:properties) >>
             str("}") >>
             space?
           ).as(:ruleset)
@@ -50,7 +52,6 @@ class Parser < Parslet::Parser
           ).as(:nested_ruleset)
         }
 
-        #rule(:blocks) { (nested_ruleset.as(:nested) | ruleset).repeat(0).as(:blocks) }
         rule(:blocks) {
           space? >> (comment | nested_ruleset | ruleset).repeat(1).as(:blocks) >> space?
         }

test/csscss/parser/css_test.rb

@@ -128,6 +128,12 @@ module Css
           rs(sel("h1"), [dec("outline", "1px")])
         ])
       end
+
+      it "ignores double semicolons" do
+        trans("h1 { display:none;;}").must_equal([
+          rs(sel("h1"), [dec("display", "none")])
+        ])
+      end
     end
   end
 end