Add support for multiple tileSizes in the tilegrid.

This is needed by WMTS.

src/ol/source/debugtilesource.js

@@ -33,7 +33,7 @@ ol.DebugTile_ = function(tileCoord, tileGrid) {
    * @private
    * @type {ol.Size}
    */
-  this.tileSize_ = tileGrid.getTileSize();
+  this.tileSize_ = tileGrid.getTileSize(tileCoord.z);
 
   /**
    * @private

src/ol/source/tiledwmssource.js

@@ -46,9 +46,6 @@ ol.source.TiledWMS = function(tiledWMSOptions) {
     'FORMAT': 'image/png',
     'TRANSPARENT': true
   };
-  var tileSize = tileGrid.getTileSize();
-  baseParams['WIDTH'] = tileSize.width;
-  baseParams['HEIGHT'] = tileSize.height;
   baseParams[version >= '1.3' ? 'CRS' : 'SRS'] = projection.getCode();
   goog.object.extend(baseParams, tiledWMSOptions.params);