[fuchsia] Update profiler assertions to allow for profiler running on a different thread.

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index 2e1d10b4a32ba9ff45afa3667183af154ffe2920..6eaca60e7084d8d77263a15ccd48d9581818e10e 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -451,8 +451,9 @@ class ProfilerDartStackWalker : public ProfilerStackWalker {
         stack_lower_(stack_lower),
         has_exit_frame_(exited_dart_code) {
     if (exited_dart_code) {
-// On windows the profiler does not run on the thread being profiled.
-#if defined(_WIN32)
+// On Windows and Fuchsia the profiler does not run on the thread being
+// profiled.
+#if defined(HOST_OS_WINDOWS) || defined(HOST_OS_FUCHSIA)
       const StackFrameIterator::CrossThreadPolicy cross_thread_policy =
           StackFrameIterator::kAllowCrossThreadIteration;
 #else