Fix GC bug with missing handle. Bug=133618

src/ia32/lithium-codegen-ia32.cc

Index: src/ia32/lithium-codegen-ia32.cc
===================================================================
--- src/ia32/lithium-codegen-ia32.cc	(revision 11873)
+++ src/ia32/lithium-codegen-ia32.cc	(working copy)
@@ -2327,15 +2327,15 @@
   } else {
     // Negative lookup.
     // Check prototypes.
-    HeapObject* current = HeapObject::cast((*type)->prototype());
+    Handle<HeapObject> current(HeapObject::cast((*type)->prototype()));
     Heap* heap = type->GetHeap();
-    while (current != heap->null_value()) {
-      Handle<HeapObject> link(current);
-      __ LoadHeapObject(result, link);
+    while (*current != heap->null_value()) {
+      __ LoadHeapObject(result, current);
       __ cmp(FieldOperand(result, HeapObject::kMapOffset),
-                          Handle<Map>(JSObject::cast(current)->map()));
+                          Handle<Map>(current->map()));
       DeoptimizeIf(not_equal, env);
-      current = HeapObject::cast(current->map()->prototype());
+      current =
+          Handle<HeapObject>(HeapObject::cast(current->map()->prototype()));
     }
     __ mov(result, factory()->undefined_value());
   }