[SPARK-20591][WEB UI] Succeeded tasks num not equal in all jobs page and job detail page on spark web ui when speculative task(s) exist.

## What changes were proposed in this pull request?

Modified succeeded num in job detail page from "completed = stageData.completedIndices.size" to "completed = stageData.numCompleteTasks",which making succeeded tasks num in all jobs page and job detail page look more consistent, and more easily to find which stages the speculative task(s) were in.

## How was this patch tested?

manual tests

Author: fjh100456 <fu.jinhua6@zte.com.cn>

Closes apache#17923 from fjh100456/master.

Author: fjh100456

core/src/main/scala/org/apache/spark/ui/jobs/AllJobsPage.scala

@@ -631,7 +631,8 @@ private[ui] class JobPagedTable(
         {if (job.numSkippedStages > 0) s"(${job.numSkippedStages} skipped)"}
       </td>
       <td class="progress-cell">
-        {UIUtils.makeProgressBar(started = job.numActiveTasks, completed = job.numCompletedTasks,
+        {UIUtils.makeProgressBar(started = job.numActiveTasks,
+        completed = job.completedIndices.size,
         failed = job.numFailedTasks, skipped = job.numSkippedTasks,
         reasonToNumKilled = job.reasonToNumKilled, total = job.numTasks - job.numSkippedTasks)}
       </td>

core/src/main/scala/org/apache/spark/ui/jobs/JobProgressListener.scala

@@ -423,6 +423,7 @@ class JobProgressListener(conf: SparkConf) extends SparkListener with Logging {
         jobData.numActiveTasks -= 1
         taskEnd.reason match {
           case Success =>
+            jobData.completedIndices.add((taskEnd.stageId, info.index))
             jobData.numCompletedTasks += 1
           case kill: TaskKilled =>
             jobData.reasonToNumKilled = jobData.reasonToNumKilled.updated(

core/src/main/scala/org/apache/spark/ui/jobs/UIData.scala

@@ -62,6 +62,7 @@ private[spark] object UIData {
     var numTasks: Int = 0,
     var numActiveTasks: Int = 0,
     var numCompletedTasks: Int = 0,
+    var completedIndices: OpenHashSet[(Int, Int)] = new OpenHashSet[(Int, Int)](),
     var numSkippedTasks: Int = 0,
     var numFailedTasks: Int = 0,
     var reasonToNumKilled: Map[String, Int] = Map.empty,

core/src/test/scala/org/apache/spark/ui/UISeleniumSuite.scala

@@ -320,12 +320,7 @@ class UISeleniumSuite extends SparkFunSuite with WebBrowser with Matchers with B
       eventually(timeout(5 seconds), interval(50 milliseconds)) {
         goToUi(sc, "/jobs")
         find(cssSelector(".stage-progress-cell")).get.text should be ("2/2 (1 failed)")
-        // Ideally, the following test would pass, but currently we overcount completed tasks
-        // if task recomputations occur:
-        // find(cssSelector(".progress-cell .progress")).get.text should be ("2/2 (1 failed)")
-        // Instead, we guarantee that the total number of tasks is always correct, while the number
-        // of completed tasks may be higher:
-        find(cssSelector(".progress-cell .progress")).get.text should be ("3/2 (1 failed)")
+        find(cssSelector(".progress-cell .progress")).get.text should be ("2/2 (1 failed)")
       }
       val jobJson = getJson(sc.ui.get, "jobs")
       (jobJson \ "numTasks").extract[Int]should be (2)