Making it so the clear method on the canvas renderer permanently clears features (as with the other renderers). r=crschmidt (closes #2775)

git-svn-id: http://svn.openlayers.org/trunk/openlayers@10595 dc9f47b5-9b13-0410-9fdd-eb0c1a62fdaf

lib/OpenLayers/Renderer/Canvas.js

@@ -393,14 +393,14 @@ OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
         var y = ((extent.top / resolution) - point.y / resolution);
         return [x, y];
     },
-        
+
     /**
      * Method: clear
      * Clear all vectors from the renderer.
-     * virtual function.
      */    
     clear: function() {
         this.canvas.clearRect(0, 0, this.root.width, this.root.height);
+        this.features = {};
     },
 
     /**
@@ -458,7 +458,7 @@ OpenLayers.Renderer.Canvas = OpenLayers.Class(OpenLayers.Renderer, {
      */
     redraw: function() {
         if (!this.locked) {
-            this.clear();
+            this.canvas.clearRect(0, 0, this.root.width, this.root.height);
             var labelMap = [];
             var feature, style;
             for (var id in this.features) {