use log2(scale) to compute mip level

expectations/gm/ignored-tests.txt

Index: expectations/gm/ignored-tests.txt
diff --git a/expectations/gm/ignored-tests.txt b/expectations/gm/ignored-tests.txt
index 6a76e6470b028329bd3198ae86af53636b92aa76..b870f1c46260edf2bac1359c0f0f6aa842667844 100644
--- a/expectations/gm/ignored-tests.txt
+++ b/expectations/gm/ignored-tests.txt
@@ -33,13 +33,6 @@
 ## epoger will rebaseline by 25 Dec 2013
 #gradtext
 
-# robertphillips - skia:2995
-blurrects
-
-# sugoi https://codereview.chromium.org/646213004/
-# New shadow only option in SkDropShadowImageFilter
-dropshadowimagefilter
-
 # reed - rebase after mipmap level improvement
 downsamplebitmap_image_medium_mandrill_512
 downsamplebitmap_image_medium_mandrill_132x132_12x12
@@ -48,9 +41,15 @@ downsamplebitmap_image_medium_mandrill_132x132_12x12.astc
 downsamplebitmap_checkerboard_medium_512_256
 downsamplebitmap_text_medium_72.00pt
 filterindiabox
-# possibly also reed?
 coloremoji
 fontmgr_iter
 
+# robertphillips - skia:2995
+blurrects
+
+# sugoi https://codereview.chromium.org/646213004/
+# New shadow only option in SkDropShadowImageFilter
+dropshadowimagefilter
+
 # fmalita - rebaseline for http://crbug.com/447707
 pictureshader