Introduce instance type for transition arrays.

src/objects-debug.cc

Index: src/objects-debug.cc
diff --git a/src/objects-debug.cc b/src/objects-debug.cc
index ee58f02ed12c583515d04cb32560f6ea2bf966c5..ca9ccb63960960dd3e70c35aca61151fb0d6a87b 100644
--- a/src/objects-debug.cc
+++ b/src/objects-debug.cc
@@ -76,6 +76,9 @@ void HeapObject::HeapObjectVerify() {
     case BYTECODE_ARRAY_TYPE:
       BytecodeArray::cast(this)->BytecodeArrayVerify();
       break;
+    case TRANSITION_ARRAY_TYPE:
+      TransitionArray::cast(this)->TransitionArrayVerify();
+      break;
     case FREE_SPACE_TYPE:
       FreeSpace::cast(this)->FreeSpaceVerify();
       break;
@@ -407,6 +410,17 @@ void FixedDoubleArray::FixedDoubleArrayVerify() {
 }
 
 
+void TransitionArray::TransitionArrayVerify() {
+  for (int i = 0; i < length(); i++) {
+    Object* e = get(i);
+    VerifyPointer(e);
+  }
+  CHECK_LE(LengthFor(number_of_transitions()), length());
+  CHECK(next_link()->IsUndefined() || next_link()->IsSmi() ||
+        next_link()->IsTransitionArray());
+}
+
+
 void JSGeneratorObject::JSGeneratorObjectVerify() {
   // In an expression like "new g()", there can be a point where a generator
   // object is allocated but its fields are all undefined, as it hasn't yet been