Make a local variable of ctx

lib/torque/renderer/point.js

@@ -67,13 +67,13 @@ var Filters = require('./torque_filters');
       var canvas = this._canvas;
       var color = this._Map['-torque-clear-color']
       // shortcut for the default value
+      var ctx = this._ctx;
       if (color  === "rgba(255, 255, 255, 0)" || !color) {
-        this._ctx.save();
-        this._ctx.setTransform(1, 0, 0, 1, 0, 0);
-        this._ctx.clearRect(0, 0, canvas.width, canvas.height);
-        this._ctx.restore();
+        ctx.save();
+        ctx.setTransform(1, 0, 0, 1, 0, 0);
+        ctx.clearRect(0, 0, canvas.width, canvas.height);
+        ctx.restore();
       } else {
-        var ctx = this._ctx;
         ctx.setTransform(1, 0, 0, 1, 0, 0);
         var compop = this._Map['comp-op']
         ctx.globalCompositeOperation = compop2canvas(compop);