Kill kWoff2FlagsContinueStream

There is only a single data stream for all the compressed tables, but
the code was originally written for separately compressed tables then
retrofitted, so this is an attempt to streamline it a bit.

src/woff2_enc.cc

@@ -340,7 +340,6 @@ bool ConvertTTFToWOFF2(const uint8_t *data, size_t length,
       } else {
         table.dst_length = 0;
         table.dst_data = NULL;
-        table.flags |= kWoff2FlagsContinueStream;
       }
       tables.push_back(table);
     }