1. Avoid potential dead lock due to lock-order-inversion

runtime/vm/runtime_entry.cc

 // Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/runtime_entry.h"
 
 #include "vm/object.h"
 #include "vm/symbols.h"
 #include "vm/verifier.h"
 
 namespace dart {
 
 #if defined(TESTING) || defined(DEBUG)
 void VerifyOnTransition() {
   Thread* thread = Thread::Current();
   TransitionGeneratedToVM transition(thread);
-  thread->isolate()->heap()->WaitForSweeperTasks();
+  thread->isolate()->heap()->WaitForSweeperTasks(thread);
   SafepointOperationScope safepoint_scope(thread);
   VerifyPointersVisitor::VerifyPointers();
   thread->isolate()->heap()->Verify();
 }
 #endif
 
 
 // Add function to a class and that class to the class dictionary so that
 // frame walking can be used.
 const Function& RegisterFakeFunction(const char* name, const Code& code) {
   Thread* thread = Thread::Current();
   const String& class_name = String::Handle(Symbols::New(thread, "ownerClass"));
   const Script& script = Script::Handle();
   const Library& lib = Library::Handle(Library::CoreLibrary());
   const Class& owner_class = Class::Handle(
       Class::New(lib, class_name, script, TokenPosition::kNoSource));
   const String& function_name = String::ZoneHandle(Symbols::New(thread, name));
   const Function& function = Function::ZoneHandle(Function::New(
       function_name, RawFunction::kRegularFunction, true, false, false, false,
       false, owner_class, TokenPosition::kMinSource));
   const Array& functions = Array::Handle(Array::New(1));
   functions.SetAt(0, function);
   owner_class.SetFunctions(functions);
   lib.AddClass(owner_class);
   function.AttachCode(code);
   return function;
 }
 
 }  // namespace dart