Let closestOnSegment return nothing more than a coordinate

Since we do not use the 'along' property anywhere, and the
resulting array returned by closestOnSegment could cause trouble
when working with 3d coodinates, now only the closest point is
returned, and the squared distance to the segment is calculated
by squaredDistanceToSegment instead.

src/ol/coordinate.js

@@ -43,13 +43,15 @@ ol.coordinate.add = function(coordinate, delta) {
 
 
 /**
+ * Calculates the point closest to the passed coordinate on the passed segment.
+ * This is the foot of the perpendicular of the coordinate to the segment when
+ * the foot is on the segment, or the closest segment coordinate when the foot
+ * is outside the segment.
+ *
  * @param {ol.Coordinate} coordinate The coordinate.
  * @param {Array.<ol.Coordinate>} segment The two coordinates of the segment.
- * @return {Array} An array compatible with ol.Coordinate, but with 4 vaules:
- *     [0] x-coordinate of the point closest to the given point on the segment;
- *     [1] y-coordinate of the point closest to the given point on the segment;
- *     [2] squared distance between given point and segment;
- *     [3] describes how far between the two segment points the given point is.
+ * @return {ol.Coordinate} The foot of the perpendicular of the coordinate to
+ *     the segment.
  */
 ol.coordinate.closestOnSegment = function(coordinate, segment) {
   var x0 = coordinate[0];
@@ -75,9 +77,7 @@ ol.coordinate.closestOnSegment = function(coordinate, segment) {
     x = x1 + along * dx;
     y = y1 + along * dy;
   }
-  var xDist = x - x0;
-  var yDist = y - y0;
-  return [x, y, xDist * xDist + yDist * yDist, along];
+  return [x, y];
 };
 
 
@@ -183,7 +183,8 @@ ol.coordinate.squaredDistance = function(coord1, coord2) {
  * @return {number} Squared distance from the point to the line segment.
  */
 ol.coordinate.squaredDistanceToSegment = function(coordinate, segment) {
-  return ol.coordinate.closestOnSegment(coordinate, segment)[2];
+  return ol.coordinate.squaredDistance(coordinate,
+      ol.coordinate.closestOnSegment(coordinate, segment));
 };
 
 

src/ol/geom/linestring.js

@@ -5,7 +5,6 @@ goog.require('goog.events.EventType');
 goog.require('ol.CoordinateArray');
 goog.require('ol.coordinate');
 goog.require('ol.extent');
-goog.require('ol.geom');
 goog.require('ol.geom.Geometry');
 goog.require('ol.geom.GeometryEvent');
 goog.require('ol.geom.GeometryType');