Disable flaky WorkerThreadTest.TerminateWorkerWhileChildIsLoading.

It was added in this CL:
https://chromium-review.googlesource.com/c/chromium/src/+/1145872

I wasn't sure whether to revert that CL or disable the test. Disabling.

It's flakily not terminated:
https://logs.chromium.org/logs/chromium/buildbucket/cr-buildbucket.appspot.com/8939871163610794448/+/steps/webkit_unit_tests_on_Windows-10-15063/0/logs/WorkerThreadTest.TerminateWorkerWhileChildIsLoading/0

TBR=japhet@chromium.org, nhiroki@chromium.org
NOTRY=True

Bug: 868253
Change-Id: I286472514666b2d11627a515fdab92e0d73cd155
Reviewed-on: https://chromium-review.googlesource.com/1152743
Commit-Queue: Henrik Boström <hbos@chromium.org>
Reviewed-by: Henrik Boström <hbos@chromium.org>
Cr-Commit-Position: refs/heads/master@{#578577}

third_party/blink/renderer/core/workers/worker_thread_test.cc

@@ -479,7 +479,9 @@ TEST_F(WorkerThreadTest, Terminate_WhileDebuggerTaskIsRunning) {
   EXPECT_EQ(ExitCode::kGracefullyTerminated, GetExitCode());
 }
 
-TEST_F(WorkerThreadTest, TerminateWorkerWhileChildIsLoading) {
+// TODO(https://crbug.com/868253): Disabled due to flaking on multiple bots.
+// Fix and re-enable.
+TEST_F(WorkerThreadTest, DISABLED_TerminateWorkerWhileChildIsLoading) {
   ExpectReportingCalls();
   Start();
   worker_thread_->WaitForInit();