gfx: Make conversions from Size to SizeF be explicit.

cc/trees/property_tree_builder.cc

Index: cc/trees/property_tree_builder.cc
diff --git a/cc/trees/property_tree_builder.cc b/cc/trees/property_tree_builder.cc
index 36d74684d7ac68430b0e2df5b542dabcb55d74de..a38ec2d8aca7406619e8a511612126ed04cb85e3 100644
--- a/cc/trees/property_tree_builder.cc
+++ b/cc/trees/property_tree_builder.cc
@@ -136,8 +136,9 @@ void AddClipNodeIfNeeded(const DataForRecursion<LayerType>& data_from_ancestor,
       transform_parent = data_for_children->transform_fixed_parent;
     }
     ClipNode node;
-    node.data.clip = gfx::RectF(
-        gfx::PointF() + layer->offset_to_transform_parent(), layer->bounds());
+    node.data.clip =
+        gfx::RectF(gfx::PointF() + layer->offset_to_transform_parent(),
+                   gfx::SizeF(layer->bounds()));
     node.data.transform_id = transform_parent->transform_tree_index();
     node.data.target_id =
         data_for_children->effect_tree->Node(data_for_children->render_target)