Reverse back wheels in webgl_demo_vehicle (#425)

* Remove unused variables in webgl_demo_vehicle/index.html
* Reverse wheels BACK_LEFT and BACK_RIGHT, the x coordinate was wrong

examples/webgl_demo_vehicle/index.html

@@ -65,7 +65,6 @@
 			// Graphics variables
 			var container, stats, speedometer;
 			var camera, controls, scene, renderer;
-			var terrainMesh, texture;
 			var clock = new THREE.Clock();
 			var materialDynamic, materialStatic, materialInteractive;
 
@@ -78,9 +77,6 @@
 
 			var syncList = [];
 			var time = 0;
-			var objectTimePeriod = 3;
-			var timeNextSpawn = time + objectTimePeriod;
-			var maxNumObjects = 30;
 
 			// Keybord actions
 			var actions = {};
@@ -339,8 +335,8 @@
 
 				addWheel(true, new Ammo.btVector3(wheelHalfTrackFront, wheelAxisHeightFront, wheelAxisFrontPosition), wheelRadiusFront, wheelWidthFront, FRONT_LEFT);
 				addWheel(true, new Ammo.btVector3(-wheelHalfTrackFront, wheelAxisHeightFront, wheelAxisFrontPosition), wheelRadiusFront, wheelWidthFront, FRONT_RIGHT);
-				addWheel(false, new Ammo.btVector3(-wheelHalfTrackBack, wheelAxisHeightBack, wheelAxisPositionBack), wheelRadiusBack, wheelWidthBack, BACK_LEFT);
-				addWheel(false, new Ammo.btVector3(wheelHalfTrackBack, wheelAxisHeightBack, wheelAxisPositionBack), wheelRadiusBack, wheelWidthBack, BACK_RIGHT);
+				addWheel(false, new Ammo.btVector3(wheelHalfTrackBack, wheelAxisHeightBack, wheelAxisPositionBack), wheelRadiusBack, wheelWidthBack, BACK_LEFT);
+				addWheel(false, new Ammo.btVector3(-wheelHalfTrackBack, wheelAxisHeightBack, wheelAxisPositionBack), wheelRadiusBack, wheelWidthBack, BACK_RIGHT);
 
 				// Sync keybord actions and physics and graphics
 				function sync(dt) {