Perform CPU sampling by CPU sampling thread only iff processing thread is not running.

src/platform-cygwin.cc

Index: src/platform-cygwin.cc
diff --git a/src/platform-cygwin.cc b/src/platform-cygwin.cc
index b39dfc0eef8aa6132fee8de5ab519d03dcabcb98..01da93d87c35e1f9e78d10c2cb199eea67e30a1f 100644
--- a/src/platform-cygwin.cc
+++ b/src/platform-cygwin.cc
@@ -692,8 +692,9 @@ class SamplerThread : public Thread {
     CONTEXT context;
     memset(&context, 0, sizeof(context));
 
-    TickSample* sample = CpuProfiler::StartTickSampleEvent(sampler->isolate());
-    if (sample == NULL) return;
+    TickSample sample_obj;
+    TickSample* sample = CpuProfiler::StartTickSampleEvent(isolate);
+    if (sample == NULL) sample = &sample_obj;
 
     static const DWORD kSuspendFailed = static_cast<DWORD>(-1);
     if (SuspendThread(profiled_thread) == kSuspendFailed) return;