Merge pull request #114 from ahocevar/noframe-fixes

Fixing IFrame tile layers. r=@elemoine

lib/OpenLayers/Tile/Image.js

@@ -339,6 +339,9 @@ OpenLayers.Tile.Image = OpenLayers.Class(OpenLayers.Tile, {
      * or if it's currently loading.
      */
     createBackBuffer: function() {
+        if (!this.imgDiv || this.isLoading) {
+            return;
+        }
         var backBuffer;
         if (this.frame) {
             backBuffer = this.frame.cloneNode(false);

lib/OpenLayers/Tile/Image/IFrame.js

@@ -204,7 +204,7 @@ OpenLayers.Tile.Image.IFrame = {
      */
     createBackBuffer: function() {
         var backBuffer;
-        if(!this.useIFrame) {
+        if(this.useIFrame === false) {
             backBuffer = OpenLayers.Tile.Image.prototype.createBackBuffer.call(this);
         }
         return backBuffer;