Bug 147407 Preview the attached report in the web viewer first time and then click the TOC button will cause NPE error
Description: It just can be reprouduced at first time preview. Step to reproduce: 1. please use attach report file 2. preview it in the web viewer 3. click the "Toggle table of contents" button Actual result: As the atteched screenshot shows,There is a NPE error.And if you preview it in the Web viewer again, the phenomenon is disappear.But reopen the eclipse and preview it at first time, it will be occured.
viewer/org.eclipse.birt.report.viewer/birt/WEB-INF/classes/org/eclipse/birt/report/utility/ParameterAccessor.java
* Deletes all files and subdirectories under dir. Returns true if all
	 * deletions were successful. If a deletion fails, the method stops
	 * attempting to delete and returns false.
	 */
	protected static boolean deleteDir( File dir )
	{
		if ( dir.isDirectory( ) )
		{
			String[] children = dir.list( );
			for ( int i = 0; i < children.length; i++ )
			{
				boolean success = deleteDir( new File( dir, children[i] ) );
				if ( !success )
				{
					return false;
				}
			}
		}
		
		return dir.delete( );
	}
	/**
	 * Get report parameter by given name.
	 * 
	 * @param request
	 *            http request
	 * @param name
	 *            parameter name
	 * @param defaultValue
	 *            default parameter value