Don't always fully repaint on viewport resize

LayoutTests/fast/repaint/window-resize-percent-html-expected.txt

Index: LayoutTests/fast/repaint/window-resize-percent-html-expected.txt
diff --git a/LayoutTests/fast/repaint/window-resize-percent-html-expected.txt b/LayoutTests/fast/repaint/window-resize-percent-html-expected.txt
index ca38c87a0e25674ddad39e8535e21a322d53dd30..6ba8698fb378031ac0186be9a7fae4917c50b419 100644
--- a/LayoutTests/fast/repaint/window-resize-percent-html-expected.txt
+++ b/LayoutTests/fast/repaint/window-resize-percent-html-expected.txt
@@ -6,9 +6,9 @@
       (contentsOpaque 1)
       (drawsContent 1)
       (repaint rects
-        (rect 0.00 0.00 200.00 200.00)
-        (rect 0.00 0.00 200.00 200.00)
-        (rect 0.00 0.00 200.00 200.00)
+        (rect 0.00 100.00 200.00 50.00)
+        (rect 0.00 100.00 200.00 50.00)
+        (rect 0.00 50.00 100.00 25.00)
       )
     )
   )
@@ -22,8 +22,6 @@
       (drawsContent 1)
       (repaint rects
         (rect 0.00 0.00 200.00 300.00)
-        (rect 0.00 0.00 200.00 300.00)
-        (rect 0.00 0.00 200.00 300.00)
       )
     )
   )
@@ -36,9 +34,10 @@
       (contentsOpaque 1)
       (drawsContent 1)
       (repaint rects
-        (rect 0.00 0.00 300.00 300.00)
-        (rect 0.00 0.00 300.00 300.00)
-        (rect 0.00 0.00 300.00 250.00)
+        (rect 0.00 250.00 300.00 50.00)
+        (rect 0.00 125.00 300.00 25.00)
+        (rect 0.00 125.00 300.00 25.00)
+        (rect 0.00 63.00 150.00 12.00)
       )
     )
   )
@@ -51,9 +50,8 @@
       (contentsOpaque 1)
       (drawsContent 1)
       (repaint rects
+        (rect 250.00 0.00 50.00 250.00)
         (rect 0.00 0.00 300.00 250.00)
-        (rect 0.00 0.00 300.00 250.00)
-        (rect 0.00 0.00 250.00 250.00)
       )
     )
   )