Add log from sync integration tests to .gitignore.

R=atwilson@chromium.org
BUG=None

Review URL: https://codereview.chromium.org/159753010

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@250756 0039d316-1c4b-4281-b951-d872f2087c98

.gitignore

@@ -178,6 +178,7 @@ v8.log
 /sdch/open-vcdiff
 /seccompsandbox
 /skia/tools/clusterfuzz-data/
+/sync_testserver.log
 /testing/gmock
 /testing/gtest
 /testing/iossim/third_party/