Bug 213671 Expose evaluate() method in IReportContext
Need Engine expose evaluate() method in IReportContext interface, this will be used to evaluate global Javascript expression in case there's no resultset bound to current report item.
engine/org.eclipse.birt.report.engine/src/org/eclipse/birt/report/engine/script/internal/ReportContextImpl.java
this.context = context;
	}
	public IReportRunnable getReportRunnable( )
	{
		return context.getRunnable( );
	}
	
	public Map getAppContext( )
	{
		return context.getAppContext( );
	}
	public void setAppContext( Map appContext )
	{
		context.setAppContext( appContext );
	}
	public void setGlobalVariable( String name, Object obj )
	{
		context.registerBean( name, obj );
	}
	public void deleteGlobalVariable( String name )
	{
		context.registerBean( name, null );
	}
	public Object getGlobalVariable( String name )
	{
		return context.getBeans( ).get( name );
	}
	public void setPersistentGlobalVariable( String name, Serializable obj )
	{
		context.registerGlobalBean( name, obj );