Bug 188029 Top face is missing in Area chart of 2D+ with negative values
Top face is missing in Area chart of 2D+ with negative values. Please see attached screenshot.
chart/org.eclipse.birt.chart.engine/src/org/eclipse/birt/chart/computation/withaxes/PlotWith2DAxes.java
dY1 -= Math.max( ( bTicksAbove ? TICK_SIZE : 0 )
								+ dAxisLabelsThickness,
								dAppliedXAxisPlotSpacing );
						dY2 += dDecorationThickness[1];
					}
					if ( iTitleLocation == ABOVE )
					{
						dY1 -= dAxisTitleThickness;
					}
					else if ( iTitleLocation == BELOW )
					{
						dY2 += dAxisTitleThickness;
					}
					
					
					if ( dY2 > dBlockStart + dBlockLength )
					{
						final double dDelta = dY2
								- ( dBlockStart + dBlockLength );
						dY2 = dBlockStart + dBlockLength;
						dY -= dDelta;
						dY1 -= dDelta;
					}
				}
				double dDelta = 0;
				if ( iv.getType( ) == IntersectionValue.MAX )
				{
					dDelta = -insCA.getTop( );
				}
				else if ( iv.getType( ) == IntersectionValue.MIN )