avoid double redraw when panning/zooming. p=tsauerwein,r=erilem (closes #2801)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10863 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Renderer/Canvas.js

@@ -67,22 +67,6 @@ OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
         return !!canvas.getContext;
     },    
     
-    /**
-     * Method: setExtent
-     * Set the visible part of the layer.
-     *
-     * Resolution has probably changed, so we nullify the resolution 
-     * cache (this.resolution), then redraw. 
-     *
-     * Parameters:
-     * extent - {<OpenLayers.Bounds>} 
-     */
-    setExtent: function(extent) {
-        this.extent = extent.clone();
-        this.resolution = null;
-        this.redraw();
-    },
-    
     /**
      * Method: setSize
      * Sets the size of the drawing surface.

tests/Renderer/Canvas.html

@@ -23,7 +23,7 @@
         
         var extent = new OpenLayers.Bounds(1,2,3,4);
         r.resolution = 1;
-        r.setExtent(extent);
+        r.setExtent(extent, true);
         t.ok(r.extent.equals(extent), "extent is correctly set");
         t.eq(r.resolution, null, "resolution nullified");
     }