Found cold start of JNLP webstart FX application fails against 7/b144 when verifying cr 6885558.

Steps to reproduce:
1. Install jre/7/b144/pro
2. via command line, do a "javaws -uninstall"
3. open cache viewer to ensure cache is empty
4. via command line, do "javaws http://javafx.com/samples/BrickBreaker/webstart/BrickBreaker.jnlp"
5. if application could NOT be launched, bug is reproduce.

(Note: there's no issue against 6u27/b03/pro, so this is a regression)

Trace/log:
==========
Java Web Start 10.0.0.144
Using JRE version 1.7.0-ea-b144 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\javafx
----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
m: print memory usage
o: trigger logging
p: reload proxy configuration
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
0-5: set trace level to <n>
----------------------------------------------------
Detected from bootclasspath: C:\\Program Files\\Java\\jre7\\lib\\deploy.jar
Could not launch from cache. Will try online mode. [Some of required resources are not cached.]
#### Java Web Start Error:
#### attempted to open sandboxed jar http://dl.javafx.com/1.3/javafx-rt-windows-i586__V1.3.1_b101.jar as a Trusted-Library

Exception:
==========
java.lang.SecurityException: attempted to open sandboxed jar http://dl.javafx.com/1.3/javafx-rt-windows-i586__V1.3.1_b101.jar as a Trusted-Library
at com.sun.deploy.security.CPCallbackHandler$ParentElement.checkResource(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.checkResource(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath$JarLoader.getResource(Unknown Source)
at com.sun.deploy.security.DeployURLClassPath.getResource(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at com.sun.jnlp.JNLPClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at com.sun.javafx.runtime.main.Main.main(Main.java:35)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at com.sun.javaws.Launcher.executeApplication(Unknown Source)
at com.sun.javaws.Launcher.executeMainClass(Unknown Source)
at com.sun.javaws.Launcher.doLaunchApp(Unknown Source)
at com.sun.javaws.Launcher.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)