[librsvg/rustification] Make condition slightly easier to read

[Federico Mena Quintero <federico src gnome org>]

commit 1e12b148dec098f2f1d5d8edfd9e0317f5e9f4ba
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Nov 11 18:15:44 2016 -0600

    Make condition slightly easier to read

 rsvg-base.c |   11 ++++++-----
 1 files changed, 6 insertions(+), 5 deletions(-)
---
diff --git a/rsvg-base.c b/rsvg-base.c
index 04b1df1..e766719 100644
--- a/rsvg-base.c
+++ b/rsvg-base.c
@@ -1422,11 +1422,12 @@ rsvg_handle_get_dimensions_sub (RsvgHandle * handle, RsvgDimensionData * dimensi
     bbox.rect.x = bbox.rect.y = 0;
     bbox.rect.width = bbox.rect.height = 1;
 
-    if (!id && (root->w.unit == LENGTH_UNIT_PERCENT || root->h.unit == LENGTH_UNIT_PERCENT)
-            && !root->vbox.active)
-        handle_subelement = TRUE;
-    else if (!id && root->w.length != -1 && root->h.length != -1)
-        handle_subelement = FALSE;
+    if (!id) {
+        if ((root->w.unit == LENGTH_UNIT_PERCENT || root->h.unit == LENGTH_UNIT_PERCENT) && 
!root->vbox.active)
+            handle_subelement = TRUE;
+        else
+            handle_subelement = FALSE;
+    }
 
     if (handle_subelement == TRUE) {
         target = cairo_image_surface_create (CAIRO_FORMAT_RGB24,