Revert "Hide Isolate pointer from embedder"

runtime/vm/isolate.cc

Index: runtime/vm/isolate.cc
diff --git a/runtime/vm/isolate.cc b/runtime/vm/isolate.cc
index 2f77c59e695043ee2a0cb3f314beba0ab9a2f657..d0fa2bf580b75618591044edf97f09ca804cfb51 100644
--- a/runtime/vm/isolate.cc
+++ b/runtime/vm/isolate.cc
@@ -1668,8 +1668,7 @@ void Isolate::TrackDeoptimizedCode(const Code& code) {
 
 
 void Isolate::WakePauseEventHandler(Dart_Isolate isolate) {
-  Isolate* iso = FindIsolateInList(isolate);
-  ASSERT(iso != NULL);
+  Isolate* iso = reinterpret_cast<Isolate*>(isolate);
   MonitorLocker ml(iso->pause_loop_monitor_);
   ml.Notify();
 }
@@ -1738,20 +1737,6 @@ intptr_t Isolate::IsolateListLength() {
 }
 
 
-Isolate* Isolate::FindIsolateInList(Dart_Isolate isolate) {
-  MonitorLocker ml(isolates_list_monitor_);
-  Isolate* current = isolates_list_head_;
-  while (current != NULL) {
-    if (Api::CastIsolate(current) == isolate) {
-      // We've found the isolate.
-      return current;
-    }
-    current = current->next_;
-  }
-  return NULL;
-}
-
-
 void Isolate::AddIsolateTolist(Isolate* isolate) {
   MonitorLocker ml(isolates_list_monitor_);
   ASSERT(isolate != NULL);