[GTK] fast/flexbox/clear-overflow-before-scroll-update.html is failing

[Zan Dobersek]

The fast/flexbox/clear-overflow-before-scroll-update.html layout test is failing on the GTK port since introduced in r151360.
http://trac.webkit.org/changeset/151360

Not sure whether this is completely OK to simply rebaseline.

--- /home/slave/webkitgtk/gtk-linux-64-release/build/layout-test-results/fast/flexbox/clear-overflow-before-scroll-update-expected.txt
+++ /home/slave/webkitgtk/gtk-linux-64-release/build/layout-test-results/fast/flexbox/clear-overflow-before-scroll-update-actual.txt
@@ -1,14 +1,14 @@
 layer at (0,0) size 800x600
   RenderView at (0,0) size 800x600
-layer at (0,0) size 800x43
-  RenderBlock {HTML} at (0,0) size 800x43
-    RenderDeprecatedFlexibleBox {BODY} at (8,8) size 784x27
-      RenderBlock (anonymous) at (0,0) size 33x27
-        RenderText {#text} at (19,4) size 4x18
-          text run at (19,4) width 4: " "
-        RenderBlock {SPAN} at (23,8) size 10x10 [bgcolor=#FF0000]
+layer at (0,0) size 800x47
+  RenderBlock {HTML} at (0,0) size 800x47
+    RenderDeprecatedFlexibleBox {BODY} at (8,8) size 784x31
+      RenderBlock (anonymous) at (0,0) size 43x31
+        RenderText {#text} at (29,7) size 4x17
+          text run at (29,7) width 4: " "
+        RenderBlock {SPAN} at (33,11) size 10x10 [bgcolor=#FF0000]
         RenderText {#text} at (0,0) size 0x0
-layer at (10,10) size 15x23 clip at (15,15) size 5x13
-  RenderMenuList {SELECT} at (2,2) size 15x23 [bgcolor=#FFFFFF] [border: (5px solid #000000)]
-    RenderBlock (anonymous) at (5,5) size 5x13
-      RenderBR at (-9999,0) size 0x13 [bgcolor=#FFFFFF]
+layer at (10,10) size 25x27 clip at (15,15) size 15x17
+  RenderMenuList {SELECT} at (2,2) size 25x27 [bgcolor=#FFFFFF] [border: (5px solid #000000)]
+    RenderBlock (anonymous) at (5,5) size 15x17
+      RenderBR at (-9999,0) size 0x17 [bgcolor=#FFFFFF]

[Gábor Ábrahám]

This test fail on Qt too.