XFA - Handle correctly nested containers with lr-tb layout (bug 1718670)

- and avoid to push a field with no dimensions when we have some available space in width in a parent.

src/core/xfa/xfa_object.js

@@ -62,6 +62,7 @@ const $isBindable = Symbol();
 const $isDataValue = Symbol();
 const $isDescendent = Symbol();
 const $isSplittable = Symbol();
+const $isThereMoreWidth = Symbol();
 const $isTransparent = Symbol();
 const $isUsable = Symbol();
 const $lastAttribute = Symbol();
@@ -185,6 +186,16 @@ class XFAObject {
     return false;
   }
 
+  /**
+     Return true if this node (typically a container)
+     can provide more width during layout.
+     The goal is to help to know what a descendant must
+     do in case of horizontal overflow.
+   */
+  [$isThereMoreWidth]() {
+    return false;
+  }
+
   [$appendChild](child) {
     child[_parent] = this;
     this[_children].push(child);
@@ -1074,6 +1085,7 @@ export {
   $isDataValue,
   $isDescendent,
   $isSplittable,
+  $isThereMoreWidth,
   $isTransparent,
   $isUsable,
   $namespaceId,