Fix NGBox's iterator logic

third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc

Index: third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc
index 213ab834004ad54493b51470c5e9bc0e99dfb654..c99af5ce609fdb19377b08686e1b8803c606ca16 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc
+++ b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.cc
@@ -156,6 +156,12 @@ void NGConstraintSpace::SetFragmentationType(NGFragmentationType type) {
   }
 }
 
+String NGConstraintSpace::toString() const {
+  return String::format("Size: %s, %s",
+                        size_.inline_size.toString().ascii().data(),
+                        size_.block_size.toString().ascii().data());
+}
+
 NGConstraintSpace* NGLayoutOpportunityIterator::Next() {
   auto* exclusions = constraint_space_->PhysicalSpace()->Exclusions();
   if (!exclusions->head())