Delete old raw .sky examples since they are no longer valid examples.

sky/examples/raw/spinning-square.sky

Index: sky/examples/raw/spinning-square.sky
diff --git a/sky/examples/raw/spinning-square.sky b/sky/examples/raw/spinning-square.sky
deleted file mode 100644
index a570732892a906c7cc7c1e4418812f5342a08e35..0000000000000000000000000000000000000000
--- a/sky/examples/raw/spinning-square.sky
+++ /dev/null
@@ -1,31 +0,0 @@
-#!mojo mojo:sky_viewer
-<sky>
-<style>
-square {
-  margin: 50px;
-  height: 100px;
-  width: 100px;
-  background-color: green;
-}
-</style>
-<square />
-<script>
-import "dart:sky";
-
-void main() {
-  Element square = document.querySelector('square');
-  double timeBase = null;
-
-  void animate(double time) {
-    if (timeBase == null)
-      timeBase = time;
-    double delta = time - timeBase;
-    int rotation = (delta / 10).floor();
-    square.style["transform"] = "rotate(${rotation}deg)";
-    window.requestAnimationFrame(animate);
-  }
-
-  window.requestAnimationFrame(animate);
-}
-</script>
-</sky>