Add command line flag for optionally loading JS from external files.

experimental/SkV8Example/sample.js

Index: experimental/SkV8Example/sample.js
diff --git a/experimental/SkV8Example/sample.js b/experimental/SkV8Example/sample.js
new file mode 100644
index 0000000000000000000000000000000000000000..3a95e551069c49bb230179098daf7a91af909c3d
--- /dev/null
+++ b/experimental/SkV8Example/sample.js
@@ -0,0 +1,13 @@
+/**
+ * @fileoverview Sample onDraw script for use with SkV8Example.
+ */
+var onDraw = function(){
+  var tick = 0;
+  function f(canvas) {
+    tick += 0.01;
+    canvas.fillStyle = '#0000ff';
+    canvas.fillRect(100, 100, Math.sin(tick)*100, Math.cos(tick)*100);
+    canvas.inval();
+  };
+  return f;
+}();