Attempt to fix flaky service test debug build failures

runtime/vm/service_event.cc

Index: runtime/vm/service_event.cc
diff --git a/runtime/vm/service_event.cc b/runtime/vm/service_event.cc
index 502a38bf72c97d4aa4f78f4c2b6657d076ccff30..d34f43981d994fb72688e3bc804e7f86fe12d86e 100644
--- a/runtime/vm/service_event.cc
+++ b/runtime/vm/service_event.cc
@@ -51,8 +51,13 @@ ServiceEvent::ServiceEvent(Isolate* isolate, EventKind event_kind)
       bytes_(NULL),
       bytes_length_(0),
       timestamp_(OS::GetCurrentTimeMillis()) {
-  if ((event_kind == ServiceEvent::kPauseStart) ||
-      (event_kind == ServiceEvent::kPauseExit)) {
+  if ((event_kind == ServiceEvent::kPauseStart) &&
+      !isolate->message_handler()->is_paused_on_start()) {
+    // We will pause on start but the message handler lacks a valid
+    // paused timestamp because we haven't paused yet. Use the current time.
+    timestamp_ = OS::GetCurrentTimeMillis();
+  } else if ((event_kind == ServiceEvent::kPauseStart) ||
+             (event_kind == ServiceEvent::kPauseExit)) {
     timestamp_ = isolate->message_handler()->paused_timestamp();
   } else if (event_kind == ServiceEvent::kResume) {
     timestamp_ = isolate->last_resume_timestamp();