Allow geometries to use a shared vertex array

The ol.geom.SharedVertices structure represents a flattened array of vertex coordinates.  This is intended to support optimal WebGL rendering.

src/ol/geom/geometry.js

@@ -1,15 +1,23 @@
-goog.require('ol.Extent');
-goog.provide('ol.geom.Coordinate');
-goog.provide('ol.geom.CoordinateArray');
 goog.provide('ol.geom.Geometry');
 goog.provide('ol.geom.GeometryType');
 
+goog.require('ol.Extent');
+goog.require('ol.geom.SharedVertices');
+
 
 
 /**
  * @constructor
  */
-ol.geom.Geometry = function() {};
+ol.geom.Geometry = function() {
+
+  /**
+   * @type {ol.geom.SharedVertices}
+   * @protected
+   */
+  this.vertices = null;
+
+};
 
 
 /**
@@ -26,6 +34,21 @@ ol.geom.Geometry.prototype.dimension;
 ol.geom.Geometry.prototype.getBounds = goog.abstractMethod;
 
 
+/**
+ * @return {Array} The GeoJSON style coordinates array for the geometry.
+ */
+ol.geom.Geometry.prototype.getCoordinates = goog.abstractMethod;
+
+
+/**
+ * Get the shared vertices for this geometry.
+ * @return {ol.geom.SharedVertices} The shared vertices.
+ */
+ol.geom.Geometry.prototype.getSharedVertices = function() {
+  return this.vertices;
+};
+
+
 /**
  * Get the geometry type.
  * @return {ol.geom.GeometryType} The geometry type.
@@ -33,18 +56,6 @@ ol.geom.Geometry.prototype.getBounds = goog.abstractMethod;
 ol.geom.Geometry.prototype.getType = goog.abstractMethod;
 
 
-/**
- * @typedef {Array.<number>}
- */
-ol.geom.Coordinate;
-
-
-/**
- * @typedef {Array.<ol.geom.Coordinate>}
- */
-ol.geom.CoordinateArray;
-
-
 /**
  * @enum {string}
  */