[timeline] Update serialization example to use ISOString dates. (#2789)

Resolves #2696

examples/timeline/dataHandling/dataSerialization.html

@@ -35,12 +35,38 @@
 
 <textarea id="data">
 [
-  {"id": 1, "content": "item 1", "start": "2014-01-01 01:00:00"},
-  {"id": 2, "content": "item 2", "start": "2014-01-01 02:00:00"},
-  {"id": 3, "content": "item 3", "start": "2014-01-01 03:00:00"},
-  {"id": 4, "content": "item 4", "start": "2014-01-01 04:00:00", "end": "2014-01-01 04:30:00"},
-  {"id": 5, "content": "item 5", "start": "2014-01-01 05:00:00", "type": "point"},
-  {"id": 6, "content": "item 6", "start": "2014-01-01 06:00:00"}
+  {
+    "id": 1,
+    "content": "item 1",
+    "start": "2014-01-01T01:00:00"
+  },
+  {
+    "id": 2,
+    "content": "item 2",
+    "start": "2014-01-01T02:00:00"
+  },
+  {
+    "id": 3,
+    "content": "item 3",
+    "start": "2014-01-01T03:00:00"
+  },
+  {
+    "id": 4,
+    "content": "item 4",
+    "start": "2014-01-01T04:00:00",
+    "end": "2014-01-01T04:30:00"
+  },
+  {
+    "id": 5,
+    "content": "item 5",
+    "start": "2014-01-01T05:00:00",
+    "type": "point"
+  },
+  {
+    "id": 6,
+    "content": "item 6",
+    "start": "2014-01-01T06:00:00"
+  }
 ]
 </textarea>