[Sass] Make :line_numbers an alias for :line_comments.

doc-src/SASS_CHANGELOG.md

@@ -8,6 +8,9 @@
 * Use `Rails.env` rather than `RAILS_ENV` when running under Rails 3.0.
   Thanks to [Duncan Grazier](http://duncangrazier.com/).
 
+* Support `:line_numbers` as an alias for {file:SASS_REFERENCE.md#line_numbers-option `:line_comments`},
+  since that's what the docs have said forever.
+
 ## [2.2.17](http://github.com/nex3/haml/commit/2.2.16)
 
 * When the {file:SASS_REFERENCE.md#full_exception-option `:full_exception` option}

doc-src/SASS_REFERENCE.md

@@ -205,6 +205,7 @@ Available options are:
   where a selector is defined to be emitted into the compiled CSS
   as a comment. Useful for debugging especially when using imports
   and mixins.
+  This option may also be called `:line_comments`.
 
 {#custom-option} `:custom`
 : An option that's available for individual applications to set

lib/sass/engine.rb

@@ -144,6 +144,10 @@ module Sass
       @options = DEFAULT_OPTIONS.merge(options.reject {|k, v| v.nil?})
       @template = template
 
+      # Support both, because the docs said one and the other actually worked
+      # for quite a long time.
+      @options[:line_comments] ||= @options[:line_numbers]
+
       # Backwards compatibility
       @options[:property_syntax] ||= @options[:attribute_syntax]
       case @options[:property_syntax]