Change == into an instance call to allow polymorphic inlining of ==.

runtime/lib/object.cc

Index: runtime/lib/object.cc
===================================================================
--- runtime/lib/object.cc	(revision 29797)
+++ runtime/lib/object.cc	(working copy)
@@ -18,6 +18,13 @@
 DECLARE_FLAG(bool, trace_type_checks);
 
 
+DEFINE_NATIVE_ENTRY(Object_equals, 1) {
+  // Implemented in the flow graph builder.
+  UNREACHABLE();
+  return Object::null();
+}
+
+
 DEFINE_NATIVE_ENTRY(Object_cid, 1) {
   const Instance& instance = Instance::CheckedHandle(arguments->NativeArgAt(0));
   return Smi::New(instance.GetClassId());