Added page scripts and styles

page-scripts/page-script-to-content-script-messaging.js

@@ -0,0 +1,18 @@
+var messenger = document.getElementById("from-page-script");
+
+messenger.addEventListener("click", messageContentScript);
+
+function messageContentScript() {
+  window.postMessage({
+    direction: "from-page-script",
+    message: "Message from the page"
+  }, "*");
+}
+
+window.addEventListener("message", function(event) {
+  if (event.source == window &&
+      event.data.direction &&
+      event.data.direction == "from-content-script") {
+    alert("Page script received message: \"" + event.data.message + "\"");
+  }
+});