[SPARK-19330][DSTREAMS] Also show tooltip for successful batches

## What changes were proposed in this pull request?

### Before
![_streaming_before](https://cloud.githubusercontent.com/assets/15843379/22181462/1e45c20c-e0c8-11e6-831c-8bf69722a4ee.png)

### After
![_streaming_after](https://cloud.githubusercontent.com/assets/15843379/22181464/23f38a40-e0c8-11e6-9a87-e27b1ffb1935.png)

## How was this patch tested?

Manually

Author: Liwei Lin <lwlin7@gmail.com>

Closes #16673 from lw-lin/streaming.

streaming/src/main/resources/org/apache/spark/streaming/ui/static/streaming-page.js

@@ -169,7 +169,7 @@ function drawTimeline(id, data, minX, maxX, minY, maxY, unitY, batchInterval) {
             .style("cursor", "pointer")
             .attr("cx", function(d) { return x(d.x); })
             .attr("cy", function(d) { return y(d.y); })
-            .attr("r", function(d) { return isFailedBatch(d.x) ? "2" : "0";})
+            .attr("r", function(d) { return isFailedBatch(d.x) ? "2" : "3";})
             .on('mouseover', function(d) {
                 var tip = formatYValue(d.y) + " " + unitY + " at " + timeFormat[d.x];
                 showBootstrapTooltip(d3.select(this).node(), tip);
@@ -187,7 +187,7 @@ function drawTimeline(id, data, minX, maxX, minY, maxY, unitY, batchInterval) {
                     .attr("stroke", function(d) { return isFailedBatch(d.x) ? "red" : "white";})
                     .attr("fill", function(d) { return isFailedBatch(d.x) ? "red" : "white";})
                     .attr("opacity", function(d) { return isFailedBatch(d.x) ? "1" : "0";})
-                    .attr("r", function(d) { return isFailedBatch(d.x) ? "2" : "0";});
+                    .attr("r", function(d) { return isFailedBatch(d.x) ? "2" : "3";});
             })
             .on("click", function(d) {
                 if (lastTimeout != null) {