[vm, gc] Require a safepoint for heap iteration.

runtime/vm/class_finalizer.cc

 // Copyright (c) 2013, 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/class_finalizer.h"
 
 #include "vm/flags.h"
 #include "vm/hash_table.h"
 #include "vm/heap.h"
 #include "vm/isolate.h"
@@ skipping 3636 matching lines @@
         obj->SetClassId(new_cid);
       }
     }
   }
 
  private:
   intptr_t* old_to_new_cids_;
 };
 
 void ClassFinalizer::RemapClassIds(intptr_t* old_to_new_cid) {
-  Isolate* I = Thread::Current()->isolate();
+  Thread* T = Thread::Current();
+  Isolate* I = T->isolate();
 
   // Code, ICData, allocation stubs have now-invalid cids.
   ClearAllCode();
 
   {
-    HeapIterationScope his;
+    HeapIterationScope his(T);
     I->set_remapping_cids(true);
 
     // Update the class table. Do it before rewriting cids in headers, as the
     // heap walkers load an object's size *after* calling the visitor.
     I->class_table()->Remap(old_to_new_cid);
 
     // Rewrite cids in headers and cids in Classes, Fields, Types and
     // TypeParameters.
     {
       CidRewriteVisitor visitor(old_to_new_cid);
@@ skipping 39 matching lines @@
   BoundedType& bounded_type_;
 };
 
 void ClassFinalizer::RehashTypes() {
   Thread* T = Thread::Current();
   Zone* Z = T->zone();
   Isolate* I = T->isolate();
 
   // Clear all cached hash values.
   {
-    HeapIterationScope his;
+    HeapIterationScope his(T);
     ClearTypeHashVisitor visitor(Z);
     I->heap()->VisitObjects(&visitor);
   }
 
   // Rehash the canonical Types table.
   ObjectStore* object_store = I->object_store();
   GrowableObjectArray& types =
       GrowableObjectArray::Handle(Z, GrowableObjectArray::New());
   Array& types_array = Array::Handle(Z);
   Type& type = Type::Handle(Z);
@@ skipping 56 matching lines @@
   ProgramVisitor::VisitFunctions(&function_visitor);
 
   class ClearCodeClassVisitor : public ClassVisitor {
     void Visit(const Class& cls) { cls.DisableAllocationStub(); }
   };
   ClearCodeClassVisitor class_visitor;
   ProgramVisitor::VisitClasses(&class_visitor);
 }
 
 }  // namespace dart