TESSENDERLO, Belgium — The European Commission is preparing new measures to prop up the EU’s chemicals industry as a wave of cheap Chinese imports pushes the sector to the brink. EU leaders will discuss a Commission effort to curb the Chinese supply glut at a summit on June 18–19. But the Brussels machinery moves slowly, and drawing up measures could take months, or even years — time Europe’s chemical manufacturers say they don’t have.   “The whole chemical industry is bleeding,” said Rudy