[layoutng] Make RunOldLayout respect IsFixedSize

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

Index: third_party/WebKit/Source/core/layout/ng/ng_constraint_space.h
diff --git a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.h b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.h
index e85a720b50816012d710a2c73bc503f2ec4395f8..ddfdd8c00dd64fa554edbed6d0943e961e3c4af9 100644
--- a/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.h
+++ b/third_party/WebKit/Source/core/layout/ng/ng_constraint_space.h
@@ -90,6 +90,8 @@ class CORE_EXPORT NGConstraintSpace final
   // grid). These flags represented whether a layout needs to produce a
   // fragment that satisfies a fixed constraint in the inline and block
   // direction respectively.
+  // If these flags are true, the AvailableSize() is interpreted as the fixed
+  // border-box size of this box in the resepective dimension.
   bool IsFixedSizeInline() const { return is_fixed_size_inline_; }
 
   bool IsFixedSizeBlock() const { return is_fixed_size_block_; }