Fix radar chart horizontal position (chartjs#4032)

Radar chart position is not center horizontally with v2.5.0.

Right and left of `furthestLimits` would be switched wrongly on
this refactoring commit.
chartjs@e1606f8

src/scales/scale.radialLinear.js

@@ -144,8 +144,8 @@ module.exports = function(Chart) {
 		// Use this to calculate the offset + change. - Make sure L/R protrusion is at least 0 to stop issues with centre points
 		var largestPossibleRadius = Math.min(scale.height / 2, scale.width / 2);
 		var furthestLimits = {
-			l: scale.width,
-			r: 0,
+			r: scale.width,
+			l: 0,
 			t: scale.height,
 			b: 0
 		};

test/specs/scale.radialLinear.tests.js

@@ -344,7 +344,7 @@ describe('Test the radial linear scale', function() {
 		});
 
 		expect(chart.scale.drawingArea).toBe(233);
-		expect(chart.scale.xCenter).toBe(247);
+		expect(chart.scale.xCenter).toBe(256);
 		expect(chart.scale.yCenter).toBe(280);
 	});
 
@@ -393,7 +393,7 @@ describe('Test the radial linear scale', function() {
 		expect(chart.scale.getDistanceFromCenterForValue(chart.scale.min)).toBe(0);
 		expect(chart.scale.getDistanceFromCenterForValue(chart.scale.max)).toBe(233);
 		expect(chart.scale.getPointPositionForValue(1, 5)).toEqual({
-			x: 261,
+			x: 270,
 			y: 275,
 		});