transitionEffect does not always work, thanks to Marco Nijdam for identifying the issue and thanks to Marc Pfister for the feedback on the dev list, p=me,r=fredj (closes #2848)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@11734 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Tile/Image.js

@@ -51,14 +51,6 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
      */
     isBackBuffer: false,
     
-    /**
-     * Property: lastRatio
-     * {Float} Used in transition code only.  This is the previous ratio
-     *     of the back buffer tile resolution to the map resolution.  Compared
-     *     with the current ratio to determine if zooming occurred.
-     */
-    lastRatio: 1,
-
     /**
      * Property: isFirstDraw
      * {Boolean} Is this the first time the tile is being drawn?
@@ -532,7 +524,7 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
         
         // if the ratio is not the same as it was last time (i.e. we are
         // zooming), then we need to adjust the backBuffer tile
-        if (ratio != this.lastRatio) {
+        if (ratio != 1) {
             if (this.layer.transitionEffect == 'resize') {
                 // In this case, we can just immediately resize the 
                 // backBufferTile.
@@ -575,7 +567,6 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
                 this.backBufferTile.hide();
             }
         }
-        this.lastRatio = ratio;
 
     },