test: Replace _TEST_CASE_ with _TEST_SUITE_ in /third_party/blink/renderer/platform/scheduler.

Googletest is (at last) converging with industry-standard terminology
[1]. We previously called test suites "test cases", which was rather
confusing for folks coming from any other testing framework.

Chrome now has a googltest version that supports _TEST_SUITE_ macros
instead of _TEST_CASE_, so this CL cleans up some of the outdated usage.

[1] https://github.com/google/googletest/blob/master/googletest/docs/primer.md#beware-of-the-nomenclature

This CL was uploaded by git cl split.

R=rmcilroy@chromium.org

Bug: 925652
Change-Id: I4aa39e130acd1831ebceded91180c15cd41ca15b
Reviewed-on: https://chromium-review.googlesource.com/c/1438374
Commit-Queue: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Alex Clarke <alexclarke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#626465}

third_party/blink/renderer/platform/scheduler/common/throttling/task_queue_throttler_unittest.cc

@@ -174,9 +174,9 @@ class TaskQueueThrottlerWithAutoAdvancingTimeTest
   DISALLOW_COPY_AND_ASSIGN(TaskQueueThrottlerWithAutoAdvancingTimeTest);
 };
 
-INSTANTIATE_TEST_CASE_P(,
-                        TaskQueueThrottlerWithAutoAdvancingTimeTest,
-                        testing::Bool());
+INSTANTIATE_TEST_SUITE_P(,
+                         TaskQueueThrottlerWithAutoAdvancingTimeTest,
+                         testing::Bool());
 
 TEST_F(TaskQueueThrottlerTest, ThrottledTasksReportRealTime) {
   EXPECT_EQ(timer_queue_->GetTimeDomain()->Now(),