Use list of isolates in profiler

runtime/vm/profiler.cc

Index: runtime/vm/profiler.cc
diff --git a/runtime/vm/profiler.cc b/runtime/vm/profiler.cc
index 529e733eccfb25b4a8fbe580a0a2e56313718ba4..cffb023bca763ed8a40e153fea02eef7a16e5931 100644
--- a/runtime/vm/profiler.cc
+++ b/runtime/vm/profiler.cc
@@ -50,6 +50,7 @@ void Profiler::InitOnce() {
   } else if (FLAG_profile_depth > kMaximumDepth) {
     FLAG_profile_depth = kMaximumDepth;
   }
+  // We must always initialize the Sample, even when the profiler is disabled.
   Sample::InitOnce();
   if (!FLAG_profile) {
     return;
@@ -57,8 +58,8 @@ void Profiler::InitOnce() {
   ASSERT(!initialized_);
   sample_buffer_ = new SampleBuffer();
   NativeSymbolResolver::InitOnce();
-  ThreadInterrupter::InitOnce();
   ThreadInterrupter::SetInterruptPeriod(FLAG_profile_period);
+  ThreadInterrupter::Startup();
   initialized_ = true;
 }