Fix VP8 border replication for very small image

Also added a test vector for this issue.

Change-Id: I8a8654f9d33b27afd53c295f1ea44d198550d067

test/test-data.sha1

diff --git a/test/test-data.sha1 b/test/test-data.sha1
index bb09b75..57c7eb3 100644
--- a/test/test-data.sha1
+++ b/test/test-data.sha1
@@ -61,6 +61,7 @@
 aff51d865c2621b60510459244ea83e958e4baed  vp80-05-sharpness-1439.ivf
 da386e72b19b5485a6af199c5eb60ef25e510dd1  vp80-05-sharpness-1440.ivf
 6759a095203d96ccd267ce09b1b050b8cc4c2f1f  vp80-05-sharpness-1443.ivf
+b95d3cc1d0df991e63e150a801710a72f20d9ba0  vp80-06-smallsize.ivf
 db55ec7fd02c864ba996ff060b25b1e08611330b  vp80-00-comprehensive-001.ivf.md5
 29db0ad011cba1e45f856d5623cd38dac3e3bf19  vp80-00-comprehensive-002.ivf.md5
 e84f258f69e173e7d68f8f8c037a0a3766902182  vp80-00-comprehensive-003.ivf.md5
@@ -122,6 +123,7 @@
 086c56378df81b6cee264d7540a7b8f2b405c7a4  vp80-05-sharpness-1439.ivf.md5
 d32dc2c4165eb266ea4c23c14a45459b363def32  vp80-05-sharpness-1440.ivf.md5
 8c69dc3d8e563f56ffab5ad1e400d9e689dd23df  vp80-05-sharpness-1443.ivf.md5
+d6f246df012c241b5fa6c1345019a3703d85c419  vp80-06-smallsize.ivf.md5
 ce881e567fe1d0fbcb2d3e9e6281a1a8d74d82e0  vp90-2-00-quantizer-00.webm
 ac5eda33407d0521c7afca43a63fd305c0cd9d13  vp90-2-00-quantizer-00.webm.md5
 2ca0463f2cfb93d25d7dded174db70b7cb87cb48  vp90-2-00-quantizer-01.webm