Update syntax of example snippets

_includes/frontpage_javascript_example1.md

@@ -1,11 +1,9 @@
 ```javascript
 actor {
-  react {
-    field this.balance = 0;
-    assert account(this.balance);
-    on message deposit($amount) {
-      this.balance += amount;
-    }
+  field this.balance = 0;
+  assert account(this.balance);
+  on message deposit($amount) {
+    this.balance += amount;
   }
 }
 ```

_includes/frontpage_javascript_example2.md

@@ -1,10 +1,8 @@
 ```javascript
 actor {
-  react {
-    on asserted account($balance) {
-      console.log("Balance:",
-                  balance);
-    }
+  on asserted account($balance) {
+    console.log("Balance:",
+                balance);
   }
 }
 ```

_includes/frontpage_racket_example1.md

@@ -1,8 +1,7 @@
 ```racket
 (actor
- (react
-  (field [balance 0])
-  (assert (account (balance)))
-  (on (message (deposit $amount))
-      (balance (+ (balance) amount)))))
+ (field [balance 0])
+ (assert (account (balance)))
+ (on (message (deposit $amount))
+     (balance (+ (balance) amount))))
 ```

_includes/frontpage_racket_example2.md

@@ -1,7 +1,6 @@
 ```racket
 (actor
- (react
-  (on (asserted (account $balance))
-      (printf "Balance: ~a\n"
-              balance))))
+ (on (asserted (account $balance))
+     (printf "Balance: ~a\n"
+             balance)))
 ```