AbstractPlotRenderer: Make private methods static where applicable

Change-Id: Iaf02502b02b2420c059f04bbe09254941301c727
Signed-off-by: Konrad Kügler <swamblumat-eclipsebugs@yahoo.de>

org.eclipse.jgit/src/org/eclipse/jgit/revplot/AbstractPlotRenderer.java

@@ -170,7 +170,7 @@ public abstract class AbstractPlotRenderer<TLane extends PlotLane, TColor> {
 	 */
 	protected abstract int drawLabel(int x, int y, Ref ref);
 
-	private int computeDotSize(final int h) {
+	private static int computeDotSize(final int h) {
 		int d = (int) (Math.min(h, LANE_WIDTH) * 0.50f);
 		d += (d & 1);
 		return d;
@@ -262,12 +262,12 @@ public abstract class AbstractPlotRenderer<TLane extends PlotLane, TColor> {
 	 */
 	protected abstract void drawText(String msg, int x, int y);
 
-	private int laneX(final PlotLane myLane) {
+	private static int laneX(final PlotLane myLane) {
 		final int p = myLane != null ? myLane.getPosition() : 0;
 		return LEFT_PAD + LANE_WIDTH * p;
 	}
 
-	private int laneC(final PlotLane myLane) {
+	private static int laneC(final PlotLane myLane) {
 		return laneX(myLane) + LANE_WIDTH / 2;
 	}
 }