Replaces LongJump with LongJumpScope.

runtime/vm/debugger.cc

Index: runtime/vm/debugger.cc
===================================================================
--- runtime/vm/debugger.cc	(revision 31435)
+++ runtime/vm/debugger.cc	(working copy)
@@ -1688,11 +1688,10 @@
   ASSERT(!getter_func.IsNull());
 
   Object& result = Object::Handle();
-  LongJump* base = isolate_->long_jump_base();
-  LongJump jump;
-  isolate_->set_long_jump_base(&jump);
   bool saved_ignore_flag = ignore_breakpoints_;
   ignore_breakpoints_ = true;
+
+  LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     const Array& args = Array::Handle(Array::New(1));
     args.SetAt(0, object);
@@ -1701,7 +1700,6 @@
     result = isolate_->object_store()->sticky_error();
   }
   ignore_breakpoints_ = saved_ignore_flag;
-  isolate_->set_long_jump_base(base);
   return result.raw();
 }
 
@@ -1727,18 +1725,15 @@
   }
 
   Object& result = Object::Handle();
-  LongJump* base = isolate_->long_jump_base();
-  LongJump jump;
-  isolate_->set_long_jump_base(&jump);
   bool saved_ignore_flag = ignore_breakpoints_;
   ignore_breakpoints_ = true;
+  LongJumpScope jump;
   if (setjmp(*jump.Set()) == 0) {
     result = DartEntry::InvokeFunction(getter_func, Object::empty_array());
   } else {
     result = isolate_->object_store()->sticky_error();
   }
   ignore_breakpoints_ = saved_ignore_flag;
-  isolate_->set_long_jump_base(base);
   return result.raw();
 }