[runtime] Allocate space for computed property names

src/objects.cc

Index: src/objects.cc
diff --git a/src/objects.cc b/src/objects.cc
index 93eacb292fdafd938cd1c141d6514d05724c98ea..ded60d3b217c56004788fae4d21591aadecf4de6 100644
--- a/src/objects.cc
+++ b/src/objects.cc
@@ -9827,6 +9827,36 @@ void FixedArray::CopyTo(int pos, FixedArray* dest, int dest_pos, int len) {
   }
 }
 
+int BoilerplateDescription::number_of_all_properties() const {
+  if (has_number_of_properties()) {
+    // If present, the last entry contains the number of properties.
+    return Smi::cast(this->get(length() - 1))->value();
+  }
+  // If the number is not given explicitly, we assume there are no
+  // properties with computed names.
+  return size();
+}
+
+int BoilerplateDescription::size() const {
+  DCHECK_EQ(0, (length() - (this->has_number_of_properties() ? 1 : 0)) % 2);
+  // Rounding is intended.
+  return length() / 2;
+}
+
+Object* BoilerplateDescription::name(int index) const {
+  // get() already checks for out of bounds access, but we do not want to allow
+  // access to the last element, if it is the number of properties.
+  DCHECK_NE(size(), index);
+  return get(2 * index);
+}
+
+Object* BoilerplateDescription::value(int index) const {
+  return get(2 * index + 1);
+}
+
+bool BoilerplateDescription::has_number_of_properties() const {
+  return length() % 2 != 0;
+}
 
 #ifdef DEBUG
 bool FixedArray::IsEqualTo(FixedArray* other) {