Don't add padding when there's no last tick.

Flot 0.8 added logic to account for the size of axis tick labels and add
padding around the edges of the plot, to prevent long labels from
sticking out.  But it padded both sides equally, which is incorrect if
the right/top side has no last axis label.

Fixed by allocating padding per-side, and checking whether the last
label would be shown before padding the top or right.  Fixes flot#1048.

jquery.flot.js

@@ -1480,7 +1480,7 @@ Licensed under the MIT license.
             // inside the canvas and isn't clipped off
 
             var minMargin = options.grid.minBorderMargin,
-                margins = { x: 0, y: 0 }, i, axis;
+                axis, i;
 
             // check stuff from the plot (FIXME: this should just read
             // a value from the series, otherwise it's impossible to
@@ -1491,21 +1491,37 @@ Licensed under the MIT license.
                     minMargin = Math.max(minMargin, 2 * (series[i].points.radius + series[i].points.lineWidth/2));
             }
 
-            margins.x = margins.y = Math.ceil(minMargin);
+            var margins = {
+                left: minMargin,
+                right: minMargin,
+                top: minMargin,
+                bottom: minMargin
+            };
 
             // check axis labels, note we don't check the actual
             // labels but instead use the overall width/height to not
             // jump as much around with replots
             $.each(allAxes(), function (_, axis) {
-                var dir = axis.direction;
-                if (axis.reserveSpace)
-                    margins[dir] = Math.ceil(Math.max(margins[dir], (dir == "x" ? axis.labelWidth : axis.labelHeight) / 2));
+                var lastTick = axis.ticks[axis.ticks.length - 1];
+                if (axis.reserveSpace && lastTick) {
+                    if (axis.direction === "x") {
+                        margins.left = Math.max(margins.left, axis.labelWidth / 2);
+                        if (lastTick.v <= axis.max) {
+                            margins.right = Math.max(margins.right, axis.labelWidth / 2);
+                        }
+                    } else {
+                        margins.bottom = Math.max(margins.bottom, axis.labelHeight / 2);
+                        if (lastTick.v <= axis.max) {
+                            margins.top = Math.max(margins.top, axis.labelHeight / 2);
+                        }
+                    }
+                }
             });
 
-            plotOffset.left = Math.max(margins.x, plotOffset.left);
-            plotOffset.right = Math.max(margins.x, plotOffset.right);
-            plotOffset.top = Math.max(margins.y, plotOffset.top);
-            plotOffset.bottom = Math.max(margins.y, plotOffset.bottom);
+            plotOffset.left = Math.ceil(Math.max(margins.left, plotOffset.left));
+            plotOffset.right = Math.ceil(Math.max(margins.right, plotOffset.right));
+            plotOffset.top = Math.ceil(Math.max(margins.top, plotOffset.top));
+            plotOffset.bottom = Math.ceil(Math.max(margins.bottom, plotOffset.bottom));
         }
 
         function setupGrid() {