Make PDF smoke test independent of Google

Change-Id: If7d25241d13ac008102d7d813cac63443b1e2077
diff --git a/ci/html2pdf b/ci/html2pdf
index 864f372..6cdc7cb 100755
--- a/ci/html2pdf
+++ b/ci/html2pdf
@@ -40,7 +40,9 @@
 </style>' "$abs_in"
 
   cd "$work_dir"
-  doc=$(basename "$abs_in")
+  # pagedown accepts absolute local paths consistently across Chrome/container
+  # versions; a bare basename can be rejected as an invalid URL.
+  doc=$abs_in
 fi
 
 # --- Automatic hyphenation ---------------------------------------------------