Include the HtmlUnitDriver in the combined client jar

Or we could just not include HtmlUnit in there, but
apparently this is what we did in 2.x

Author: shs96c

java/client/src/org/openqa/selenium/BUCK

@@ -171,6 +171,7 @@ java_library(
     "//java/client/src/org/openqa/selenium/support:support",
     "//third_party/java/htmlunit:htmlunit",
     "//third_party/java/phantomjs-driver:phantomjs-driver",
+    '//third_party/java/selenium:htmlunit-driver'
   ],
   visibility = [
     '//java/server/src/org/openqa/grid/selenium:classes',

third_party/java/selenium/BUCK

@@ -8,6 +8,7 @@ prebuilt_jar(
     '//third_party/java/htmlunit:htmlunit'
   ],
   visibility = [
+    '//java/client/src/org/openqa/selenium:client-combined',
     '//java/client/test/org/openqa/selenium/htmlunit:htmlunit',
     '//java/client/test/org/openqa/selenium/htmlunit:htmlunit-no-js',
     '//java/client/test/org/openqa/selenium/testing:test-base',