Update BoxDecoration and RenderParagraph to use sky.Color instead of int.

sky/sdk/lib/framework/rendering/paragraph.dart

Index: sky/sdk/lib/framework/rendering/paragraph.dart
diff --git a/sky/sdk/lib/framework/rendering/paragraph.dart b/sky/sdk/lib/framework/rendering/paragraph.dart
index da95ce43e1706aa6e7ae23e481a3eb47f57d4e16..92c48c9120ef38b5923b6128f57f5fbc5ea9c409 100644
--- a/sky/sdk/lib/framework/rendering/paragraph.dart
+++ b/sky/sdk/lib/framework/rendering/paragraph.dart
@@ -16,7 +16,7 @@ class RenderParagraph extends RenderBox {
 
   RenderParagraph({
     String text,
-    int color
+    sky.Color color
   }) : _color = color {
     _layoutRoot.rootElement = _document.createElement('p');
     this.text = text;
@@ -31,9 +31,9 @@ class RenderParagraph extends RenderBox {
     markNeedsLayout();
   }
 
-  int _color = 0xFF000000;
-  int get color => _color;
-  void set color (int value) {
+  sky.Color _color = sky.Color.black;
+  sky.Color get color => _color;
+  void set color (sky.Color value) {
     if (_color != value) {
       _color = value;
       markNeedsPaint();