add some compatibility options to uglifyjs:

• --v8 and --webkit for improved browser support,
  we will skip on --ie though I think
• --no-module which is undocumented but may work around
  mishoo/UglifyJS#5967

Author: mirabilos

Diff for: scripts/build-js.sh

@@ -110,6 +110,7 @@ rm -rf src
 ../scripts/smap-out.py dygraph.min.tmp.js /dev/null dygraph.min.tmp.js.map
 
 uglifyjs \
+    --no-module --v8 --webkit \
     --compress \
     --mangle \
     --output-opts "preamble='$header'" \