Fix style

Author: Andrew Or

core/src/test/scala/org/apache/spark/scheduler/TaskContextSuite.scala

@@ -23,8 +23,8 @@ import org.scalatest.BeforeAndAfter
 
 import org.apache.spark._
 import org.apache.spark.executor.TaskMetricsSuite
-import org.apache.spark.metrics.source.JvmSource
 import org.apache.spark.memory.TaskMemoryManager
+import org.apache.spark.metrics.source.JvmSource
 import org.apache.spark.network.util.JavaUtils
 import org.apache.spark.rdd.RDD
 import org.apache.spark.util.{TaskCompletionListener, TaskCompletionListenerException}