[Sass] Fix a bug with comments that shouldn't be rendered.

Closes gh-4

lib/sass/tree/attr_node.rb

@@ -35,6 +35,7 @@ module Sass::Tree
       end
       
       children.each do |kid|
+        next if kid.invisible?
         to_return << kid.to_s(tabs, real_name) << join_string
       end
       

lib/sass/tree/comment_node.rb

@@ -20,11 +20,22 @@ module Sass::Tree
     end
 
     def to_s(tabs = 0, parent_name = nil)
-      return if (@style == :compressed || silent?)
+      return if invisible?
 
       spaces = '  ' * (tabs - 1)
       spaces + "/* " + ([value] + lines.map {|l| l.text}).
         map{|l| l.sub(%r{ ?\*/ *$},'')}.join(@style == :compact ? ' ' : "\n#{spaces} * ") + " */"
     end
+
+    def invisible?
+      @style == :compressed || silent?
+    end
+
+    protected
+
+    def _perform(environment)
+      return [] if silent?
+      self
+    end
   end
 end

lib/sass/tree/directive_node.rb

@@ -19,6 +19,7 @@ module Sass::Tree
         was_attr = false
         first = true
         children.each do |child|
+          next if child.invisible?
           if @style == :compact
             if child.is_a?(AttrNode)
               result << "#{child.to_s(first || was_attr ? 1 : tabs + 1)} "

lib/sass/tree/node.rb

@@ -27,14 +27,16 @@ module Sass
         self.class == other.class && other.children == children
       end
 
+      def invisible?; false; end
+
       def to_s
         result = String.new
         children.each do |child|
           if child.is_a? AttrNode
             raise Sass::SyntaxError.new('Attributes aren\'t allowed at the root of a document.', child.line)
           else
+            next if child.invisible?
             child_str = child.to_s(1)
-            next unless child_str && child_str.length > 0
             result << child_str + (@style == :compressed ? '' : "\n")
           end
         end

lib/sass/tree/rule_node.rb

@@ -40,6 +40,7 @@ module Sass::Tree
       end.join(line_separator)
 
       children.each do |child|
+        next if child.invisible?
         if child.is_a? RuleNode
           sub_rules << child
         else

test/sass/engine_test.rb

@@ -681,6 +681,50 @@ a
 SASS
   end
 
+  # Regression tests
+
+  def test_comment_beneath_attr
+    assert_equal(<<RESULT, render(<<SOURCE))
+.box {
+  border-style: solid; }
+RESULT
+.box
+  :border
+    //:color black
+    :style solid
+SOURCE
+
+    assert_equal(<<RESULT, render(<<SOURCE))
+.box {
+  /* :color black */
+  border-style: solid; }
+RESULT
+.box
+  :border
+    /*:color black
+    :style solid
+SOURCE
+
+    assert_equal(<<RESULT, render(<<SOURCE, :style => :compressed))
+.box{border-style:solid}
+RESULT
+.box
+  :border
+    /*:color black
+    :style solid
+SOURCE
+  end
+
+  def test_compressed_comment_beneath_directive
+    assert_equal(<<RESULT, render(<<SOURCE, :style => :compressed))
+@foo{a:b}
+RESULT
+@foo
+  a: b
+  /*b: c
+SOURCE
+  end
+
   private
   
   def render(sass, options = {})