handle missing gradient arguments.

lib/compass/sass_extensions/functions/gradient_support.rb

@@ -60,9 +60,9 @@ module Compass::SassExtensions::Functions::GradientSupport
     end
     def to_webkit
       args = [
-        grad_point(position_or_angle),
+        grad_point(position_or_angle || Sass::Script::String.new("center center")),
         "0",
-        grad_point(position_or_angle),
+        grad_point(position_or_angle || Sass::Script::String.new("center center")),
         grad_end_position(color_stops, Sass::Script::Bool.new(true)),
         grad_color_stops(color_stops)
       ]
@@ -74,7 +74,7 @@ module Compass::SassExtensions::Functions::GradientSupport
     end
     def to_svg
       # XXX Add shape support if possible
-      radial_svg_gradient(color_stops, position_or_angle)
+      radial_svg_gradient(color_stops, position_or_angle || Sass::Script::String.new("center center"))
     end
   end
 
@@ -97,18 +97,17 @@ module Compass::SassExtensions::Functions::GradientSupport
       s << ")"
     end
     def to_webkit
-      args = [
+      args = []
-        grad_point(position_or_angle),
+      args << grad_point(position_or_angle || Sass::Script::String.new("top"))
-        grad_point(opposite_position(position_or_angle)),
+      args << grad_point(opposite_position(position_or_angle || Sass::Script::String.new("top")))
-        grad_color_stops(color_stops)
+      args << grad_color_stops(color_stops)
-      ]
       Sass::Script::String.new("-webkit-gradient(linear, #{args.join(', ')})")
     end
     def to_moz
       Sass::Script::String.new("-moz-#{to_s}")
     end
     def to_svg
-      linear_svg_gradient(color_stops, position_or_angle)
+      linear_svg_gradient(color_stops, position_or_angle || Sass::Script::String.new("top"))
     end
   end
 
@@ -262,7 +261,7 @@ module Compass::SassExtensions::Functions::GradientSupport
     end
 
     %w(webkit moz o ms svg).each do |prefix|
-      class_eval <<-RUBY
+      class_eval <<-RUBY, __FILE__, __LINE__ + 1
         def _#{prefix}(*args)
           args.map!{|a| a.is_a?(List) ? a.values : a}.flatten!
           List.new(*args.map!{|a| a.respond_to?(:to_#{prefix}) ? a.to_#{prefix} : a})

test/fixtures/stylesheets/compass/css/gradients.css

@@ -19,6 +19,16 @@
   background-image: url('/images/4x6.png?busted=true'), url('data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz4gPHN2ZyB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+IDxkZWZzPiA8bGluZWFyR3JhZGllbnQgaWQ9ImdyYWQiIHgxPSIwJSIgeTE9IjAlIiB4Mj0iMTAwJSIgeTI9IjEwMCUiPiA8c3RvcCBvZmZzZXQ9IjAlIiBzdG9wLWNvbG9yPSIjZGRkZGRkIiAvPjxzdG9wIG9mZnNldD0iMTAwJSIgc3RvcC1jb2xvcj0iI2FhYWFhYSIgLz4gPC9saW5lYXJHcmFkaWVudD4gPC9kZWZzPiA8cmVjdCB4PSIwIiB5PSIwIiB3aWR0aD0iMTAwJSIgaGVpZ2h0PSIxMDAlIiBmaWxsPSJ1cmwoI2dyYWQpIiAvPiA8L3N2Zz4g'), url('data:image/svg+xml;base64,PD94bWwgdmVyc2lvbj0iMS4wIiBlbmNvZGluZz0idXRmLTgiPz4gPHN2ZyB2ZXJzaW9uPSIxLjEiIHhtbG5zPSJodHRwOi8vd3d3LnczLm9yZy8yMDAwL3N2ZyI+IDxkZWZzPiA8cmFkaWFsR3JhZGllbnQgaWQ9ImdyYWQiIGdyYWRpZW50VW5pdHM9InVzZXJTcGFjZU9uVXNlIiBjeD0iNTAlIiBjeT0iNTAlIiByPSIxMDAiPiA8c3RvcCBvZmZzZXQ9IjAlIiBzdG9wLWNvbG9yPSIjZGRkZGRkIiAvPjxzdG9wIG9mZnNldD0iMTAwJSIgc3RvcC1jb2xvcj0iI2FhYWFhYSIgLz4gPC9yYWRpYWxHcmFkaWVudD4gPC9kZWZzPiA8cmVjdCB4PSIwIiB5PSIwIiB3aWR0aD0iMTAwJSIgaGVpZ2h0PSIxMDAlIiBmaWxsPSJ1cmwoI2dyYWQpIiAvPiA8L3N2Zz4g');
   background-image: url('/images/4x6.png?busted=true'), linear-gradient(top left, #dddddd 0%, #aaaaaa 100%), radial-gradient(center center, #dddddd 0%, #aaaaaa 100px); }
 
+.bg-linear-gradient-no-position {
+  background-image: -webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #dddddd), color-stop(100%, #aaaaaa));
+  background-image: -moz-linear-gradient(#dddddd 0%, #aaaaaa 100%);
+  background-image: linear-gradient(#dddddd 0%, #aaaaaa 100%); }
+
+.bg-radial-gradient-no-position {
+  background-image: -webkit-gradient(radial, 50% 50%, 0, 50% 50%, 100, color-stop(0%, #dddddd), color-stop(100%, #aaaaaa));
+  background-image: -moz-radial-gradient(#dddddd 0%, #aaaaaa 100px);
+  background-image: radial-gradient(#dddddd 0%, #aaaaaa 100px); }
+
 .linear-1 {
   background-image: -webkit-gradient(linear, 50% 0%, 50% 100%, color-stop(0%, #dddddd), color-stop(100%, #aaaaaa));
   background-image: -moz-linear-gradient(top, #dddddd 0%, #aaaaaa 100%);

test/fixtures/stylesheets/compass/sass/gradients.sass

@@ -13,6 +13,13 @@ $experimental-support-for-svg: true
 .bg-all-gradient-types
   +background-image(image-url("4x6.png"), linear-gradient(top left, #ddd, #aaa), radial-gradient(center center, #ddd, #aaa 100px))
 $experimental-support-for-svg: false
+
+.bg-linear-gradient-no-position
+  +background-image(linear-gradient(#ddd, #aaa))
+
+.bg-radial-gradient-no-position
+  +background-image(radial-gradient(#ddd, #aaa 100px))
+
 .linear-1
   +linear-gradient(color-stops(#dddddd, #aaaaaa))