[librsvg] Fix rounding in FilterContext::compute_bounds()

[Federico Mena Quintero <federico src gnome org>]

commit 3a46343abb84cac62e8a191263842ded88069326
Author: Ivan Molodetskikh <yalterz gmail com>
Date:   Sat May 26 11:41:55 2018 +0300

    Fix rounding in FilterContext::compute_bounds()

 rsvg_internals/src/filter_context.rs                |   8 ++++----
 .../reftests/svg1.1/filters-composite-02-b-ref.png  | Bin 15845 -> 15874 bytes
 2 files changed, 4 insertions(+), 4 deletions(-)
---
diff --git a/rsvg_internals/src/filter_context.rs b/rsvg_internals/src/filter_context.rs
index 2ab98ded..8a63b22e 100644
--- a/rsvg_internals/src/filter_context.rs
+++ b/rsvg_internals/src/filter_context.rs
@@ -252,10 +252,10 @@ impl FilterContext {
 
         let bbox_rect = bbox.rect.unwrap();
         IRect {
-            x0: bbox_rect.x as i32,
-            y0: bbox_rect.y as i32,
-            x1: (bbox_rect.x + bbox_rect.width) as i32,
-            y1: (bbox_rect.y + bbox_rect.height) as i32,
+            x0: bbox_rect.x.floor() as i32,
+            y0: bbox_rect.y.floor() as i32,
+            x1: (bbox_rect.x + bbox_rect.width).ceil() as i32,
+            y1: (bbox_rect.y + bbox_rect.height).ceil() as i32,
         }
     }
 }
diff --git a/tests/fixtures/reftests/svg1.1/filters-composite-02-b-ref.png 
b/tests/fixtures/reftests/svg1.1/filters-composite-02-b-ref.png
index 1806b795..4c14ff8f 100644
Binary files a/tests/fixtures/reftests/svg1.1/filters-composite-02-b-ref.png and 
b/tests/fixtures/reftests/svg1.1/filters-composite-02-b-ref.png differ