Srcset resource selection use a geometric mean to determine resource.

LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html

Index: LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html
diff --git a/LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html b/LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html
index 2631e60ba5886f42e6f458674d463f69b7c35234..575fba1493428529629a0e19f19352ca7776d271 100644
--- a/LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html
+++ b/LayoutTests/fast/dom/HTMLImageElement/image-sizes-1x.html
@@ -47,7 +47,7 @@
 <!-- Make sure that the img src is not picked when 'w' is present -->
 <img id="src_and_w" src="../../hidpi/resources/image-set-1x.png" sizes="700px" srcset="resources/image-set-4x.png 1600w">
 <img id="src_and_w2" src="../../hidpi/resources/image-set-2x.png" sizes="700px" srcset="../../hidpi/resources/image-set-1x.png 400w">
-<img id="x_and_w" sizes="700px" srcset="../../hidpi/resources/image-set-1x.png 0.5x, resources/image-set-4x.png 1600w">
+<img id="x_and_w" sizes="700px" srcset="../../hidpi/resources/image-set-1x.png 0.4x, resources/image-set-4x.png 1600w">
 <!-- The 'x' resource should be picked, and 'sizes' have no impact on its intrisic size -->
 <img id="x_and_w2" sizes="700px" srcset="../../hidpi/resources/image-set-2x.png 2x, resources/image-set-4x.png 16000w">
 <img id="x_and_w3" sizes="700px" srcset="resources/image-set-4x.png 16000w, ../../hidpi/resources/image-set-2x.png 2x">