Satisfy JSLint

JSLint complains about functions being declared in blocks.

src/ol/renderer/webgl/webgltilelayerrenderer.js

@@ -365,10 +365,10 @@ ol.renderer.webgl.TileLayer.prototype.renderFrame =
     var tilesToDrawByZ = {};
     tilesToDrawByZ[z] = {};
 
-    function isLoaded(tile) {
+    var isLoaded = function(tile) {
       return !goog.isNull(tile) && tile.getState() == ol.TileState.LOADED &&
           mapRenderer.isTileTextureLoaded(tile);
-    }
+    };
     var findLoadedTiles = goog.bind(tileSource.findLoadedTiles, tileSource,
         tilesToDrawByZ, isLoaded);