simplexml fixes for text children and casting

- fixes text children count and bool cast of empty nodes

hphp/runtime/ext/ext_simplexml.cpp

@@ -524,7 +524,9 @@ Object c_SimpleXMLElement::t_children(CStrRef ns /* = "" */,
   elem->m_is_text = m_is_text;
   elem->m_free_text = m_free_text;
   elem->m_is_children = true;
-  if (ns.empty()) {
+  if (m_is_text) {
+    // text nodes don't have children
+  } else if (ns.empty()) {
     elem->m_children.assignRef(m_children);
   } else {
     Array props = Array::Create();
@@ -873,7 +875,9 @@ Variant c_SimpleXMLElement::t___set(Variant name, Variant value) {
 }
 
 bool c_SimpleXMLElement::o_toBooleanImpl() const noexcept {
-  return (m_node || getDynProps().size());
+  return (m_node || getDynProps().size()) &&
+         (m_node->parent->type != XML_DOCUMENT_NODE ||
+          m_children.toArray().size());
 }
 
 int64_t c_SimpleXMLElement::o_toInt64Impl() const noexcept {

hphp/test/slow/simple_xml/boolean_cast.php

@@ -0,0 +1,7 @@
+<?php
+
+$element = new SimpleXMLElement('<root />');
+var_dump((bool)$element);
+
+$element = new SimpleXMLElement('<root><child /></root>');
+var_dump((bool)$element->child);

hphp/test/slow/simple_xml/boolean_cast.php.expect

@@ -0,0 +1,2 @@
+bool(false)
+bool(true)

hphp/test/slow/simple_xml/text_children.php

@@ -0,0 +1,4 @@
+<?php
+
+$element = simplexml_load_string('<root><hello>world</hello></root>');
+var_dump($element->hello->children());

hphp/test/slow/simple_xml/text_children.php.expect

@@ -0,0 +1,2 @@
+object(SimpleXMLElement)#4 (0) {
+}