Upgrade html-types to 1.0.8

This upgrade gives us access to the LegacyConversions class, which we
need to migrate off a deprecated Soy class.

Change-Id: I4113d743ac48730df0eaa900c5e4c19c2b139c5b

WORKSPACE

diff --git a/WORKSPACE b/WORKSPACE
index b5dbf05..1511bca 100644
--- a/WORKSPACE
+++ b/WORKSPACE
@@ -136,8 +136,8 @@
 
 maven_jar(
     name = "html-types",
-    artifact = "com.google.common.html.types:types:1.0.4",
-    sha1 = "2adf4c8bfccc0ff7346f9186ac5aa57d829ad065",
+    artifact = "com.google.common.html.types:types:1.0.8",
+    sha1 = "9e9cf7bc4b2a60efeb5f5581fe46d17c068e0777",
 )
 
 maven_jar(