Bug 188283 Bubbles should be z-sorted by size in Bubble charts
Biggest bubbles should be drawn first so that there is no small bubble hidden by a bigger one.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/render/DeferredCache.java
{
					wi = (WrappedInstruction) obj;
					if ( wi.isModel( ) )
					{
						ArrayList al = wi.getModel( );
						for ( int j = 0; j < al.size( ); j++ )
						{
							PrimitiveRenderEvent pre = (PrimitiveRenderEvent) al.get( j );
							pre.fill( idr );
							pre.draw( idr );
						}
					}
					else
					{
						wi.getEvent( ).iObjIndex = i + 1;
						switch ( wi.getInstruction( ) )
						{
							case PrimitiveRenderEvent.FILL
									| PrimitiveRenderEvent.DRAW :
								wi.getEvent( ).fill( idr );
								wi.getEvent( ).draw( idr );
								break;
							case PrimitiveRenderEvent.FILL :
								wi.getEvent( ).fill( idr );
								break;
							case PrimitiveRenderEvent.DRAW :
								wi.getEvent( ).draw( idr );
								break;
						}
					}