Bump picture version for uniqueID-less SkImageFilter.

Remove writing of the uniqueID, and put reading behind a version check.

BUG=skia:3559

Review URL: https://codereview.chromium.org/1010433003
diff --git a/src/core/SkReadBuffer.h b/src/core/SkReadBuffer.h
index a24ca55..65255e6 100644
--- a/src/core/SkReadBuffer.h
+++ b/src/core/SkReadBuffer.h
@@ -55,6 +55,7 @@
         kDropShadowMode_Version            = 37,
         kPictureImageFilterResolution_Version = 38,
         kPictureImageFilterLevel_Version   = 39,
+        kImageFilterNoUniqueID_Version     = 40,
     };
 
     /**