Bug 1570081 - Put the blob dirty rect in the same space as the drawing commands and visible rect. r=jrmuizel

Depends on D43222

Differential Revision: https://phabricator.services.mozilla.com/D43223

--HG--
extra : moz-landing-system : lando

gfx/layers/wr/WebRenderCommandBuilder.cpp

@@ -715,8 +715,7 @@ struct DIGroup {
 
       // Convert mInvalidRect to image space by subtracting the corner of the
       // image bounds
-      auto dirtyRect = ViewAs<ImagePixel>(
-          mInvalidRect - mVisibleRect.ToUnknownRect().TopLeft());
+      auto dirtyRect = ViewAs<ImagePixel>(mInvalidRect);
 
       auto bottomRight = dirtyRect.BottomRight();
       GP("check invalid %d %d - %d %d\n", bottomRight.x, bottomRight.y,

gfx/webrender_bindings/src/moz2d_renderer.rs

@@ -380,7 +380,7 @@ impl<'a> CachedReader<'a> {
 /// the first not-yet-copied item with those bounds in the old list and copy that.
 /// Any items found in the old list but not the new one can be safely assumed to
 /// have been deleted.
-fn merge_blob_images(old_buf: &[u8], new_buf: &[u8], mut dirty_rect: Box2d) -> Vec<u8> {
+fn merge_blob_images(old_buf: &[u8], new_buf: &[u8], dirty_rect: Box2d) -> Vec<u8> {
 
     let mut result = BlobWriter::new();
     dlog!("dirty rect: {:?}", dirty_rect);
@@ -395,11 +395,6 @@ fn merge_blob_images(old_buf: &[u8], new_buf: &[u8], mut dirty_rect: Box2d) -> V
     // we currently only support merging blobs that have the same origin
     assert_eq!(old_reader.reader.origin, new_reader.origin);
 
-    dirty_rect.x1 += new_reader.origin.x;
-    dirty_rect.y1 += new_reader.origin.y;
-    dirty_rect.x2 += new_reader.origin.x;
-    dirty_rect.y2 += new_reader.origin.y;
-
     // Loop over both new and old entries merging them.
     // Both new and old must have the same number of entries that
     // overlap but are not contained by the dirty rect, and they