Fix for issue-7157 - set the stack marker in the top API local scope just before entering dart code…

vm/dart_api_state.h

 // Copyright (c) 2012, 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.
 
 #ifndef VM_DART_API_STATE_H_
 #define VM_DART_API_STATE_H_
 
 #include "include/dart_api.h"
 
 #include "platform/thread.h"
@@ skipping 551 matching lines @@
   }
 
   WeakReferenceSet* delayed_weak_reference_sets() {
     return delayed_weak_reference_sets_;
   }
   void set_delayed_weak_reference_sets(WeakReferenceSet* reference_set) {
     delayed_weak_reference_sets_ = reference_set;
   }
 
   void UnwindScopes(uword sp) {
-    while (top_scope_ != NULL && top_scope_->stack_marker() < sp) {
+    while (top_scope_ != NULL &&
+           top_scope_->stack_marker() != 0 &&
+           top_scope_->stack_marker() <= sp) {
       ApiLocalScope* scope = top_scope_;
       top_scope_ = top_scope_->previous();
       delete scope;
     }
   }
 
   void VisitObjectPointers(ObjectPointerVisitor* visitor,
                            bool visit_prologue_weak_handles) {
     ApiLocalScope* scope = top_scope_;
     while (scope != NULL) {
@@ skipping 151 matching lines @@
           ApiNativeScope::Current()->zone()) {}
   ApiGrowableArray()
       : BaseGrowableArray<T, ValueObject>(
           ApiNativeScope::Current()->zone()) {}
 };
 
 
 }  // namespace dart
 
 #endif  // VM_DART_API_STATE_H_