Increase Stack Size for ant tests, to prevent test failures (address issue 6100)

Review at http://gwt-code-reviews.appspot.com/1369806


git-svn-id: https://google-web-toolkit.googlecode.com/svn/trunk@9806 8db76d5a-ed1c-0410-87a9-c151d255dfc7

common.ant.xml

diff --git a/common.ant.xml b/common.ant.xml
index ea0d870..845d205 100755
--- a/common.ant.xml
+++ b/common.ant.xml
@@ -210,7 +210,7 @@
       <junit dir="@{test.out}" fork="yes" printsummary="yes"
              failureproperty="junit.failure" tempdir="@{test.out}">
         <jvmarg line="-Xmx768m" />
-        <jvmarg line="-Xss512k" />
+        <jvmarg line="-Xss4M" />
         <jvmarg value="-Demma.coverage.out.file=@{test.emma.coverage}/coverage.emma" />
         <jvmarg value="-Demma.coverage.out.merge=true" />
         <jvmarg value="-Dcom.google.gwt.junit.reportPath=reports" />