After the Bell: Shares of Synopsys Tumble  NEW YORK (Reuters) - Shares of Synopsys Inc. &lt;A HREF="http://www.investor.reuters.com/FullQuote.aspx?ticker=SNPS.O target=/stocks/quickinfo/fullquote"&gt;SNPS.O&lt;/A&gt;  tumbled on Wednesday after the semiconductor design software  maker reported lower third-quarter net income and said  fourth-quarter earnings and revenues would be below Wall Street  estimates.