RFR 7147666 : High lock time for com.sun.org.apache.xerces.internal.impl.dv.DTDDVFactory.getInstance()

[Joe Wang]

Hi all,

This is a low risk, proven patch made in Xerces back in 2007 [1], 
removing unnecessary "synchronization" in DTDDVFactory.  As reported in 
7147666, this patch improves performance in one of the xml test.

Webrev : http://cr.openjdk.java.net/~joehw/7u4/cr7147666/webrev/

[1] http://svn.apache.org/viewvc?view=revision&revision=558581

Please review.

Thanks,
Joe