Add isolate tag-profile and better handling of errors

runtime/vm/thread_interrupter.cc

Index: runtime/vm/thread_interrupter.cc
diff --git a/runtime/vm/thread_interrupter.cc b/runtime/vm/thread_interrupter.cc
index d2858f71c74c1f2f1061d6fb6396c7da7baf298c..c15e05294255a6b93e86628c6b74ec1a8996d782 100644
--- a/runtime/vm/thread_interrupter.cc
+++ b/runtime/vm/thread_interrupter.cc
@@ -220,12 +220,7 @@ class ThreadInterrupterVisitIsolates : public IsolateVisitor {
   ThreadInterrupterVisitIsolates() { }
   void VisitIsolate(Isolate* isolate) {
     ASSERT(isolate != NULL);
-    InterruptableThreadState* state = isolate->thread_state();
-    if (state == NULL) {
-      return;
-    }
-    ASSERT(state->id != Thread::kInvalidThreadId);
-    ThreadInterrupter::InterruptThread(state);
+    isolate->ProfileInterrupt();
   }
 };