Fix a bug in Equals for UseVal and ConstantVal.

runtime/vm/intermediate_language_test.cc

Index: runtime/vm/intermediate_language_test.cc
===================================================================
--- runtime/vm/intermediate_language_test.cc	(revision 11030)
+++ runtime/vm/intermediate_language_test.cc	(working copy)
@@ -47,4 +47,23 @@
   EXPECT(use4->definition() == def1);
 }
 
+TEST_CASE(OptimizationTests) {
+  Definition* def1 = new PhiInstr(0);
+  Definition* def2 = new PhiInstr(0);
+  UseVal* use1a = new UseVal(def1);
+  UseVal* use1b = new UseVal(def1);
+  EXPECT(use1a->Equals(use1b));
+  EXPECT(use1a->Hashcode() == use1b->Hashcode());
+  UseVal* use2 = new UseVal(def2);
+  EXPECT(!use2->Equals(use1a));
+
+  ConstantVal* c1 = new ConstantVal(Bool::ZoneHandle(Bool::True()));
+  ConstantVal* c2 = new ConstantVal(Bool::ZoneHandle(Bool::True()));
+  EXPECT(c1->Equals(c2));
+  ConstantVal* c3 = new ConstantVal(Object::ZoneHandle());
+  ConstantVal* c4 = new ConstantVal(Object::ZoneHandle());
+  EXPECT(c3->Equals(c4));
+  EXPECT(!c3->Equals(c1));
+}
+
 }  // namespace dart