[ubsan] Fix HeapObjectMatcher to avoid invalid casts.

test/cctest/compiler/test-representation-change.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits>
 
 #include "src/v8.h"
 #include "test/cctest/cctest.h"
 #include "test/cctest/compiler/codegen-tester.h"
 #include "test/cctest/compiler/graph-builder-tester.h"
@@ skipping 51 matching lines @@
     CheckDoubleEq(expected, m.Value());
   }
 
   void CheckFloat32Constant(Node* n, float expected) {
     CHECK_EQ(IrOpcode::kFloat32Constant, n->opcode());
     float fval = OpParameter<float>(n->op());
     CHECK_EQ(expected, fval);
   }
 
   void CheckHeapConstant(Node* n, HeapObject* expected) {
-    HeapObjectMatcher<HeapObject> m(n);
+    HeapObjectMatcher m(n);
     CHECK(m.HasValue());
     CHECK_EQ(expected, *m.Value().handle());
   }
 
   void CheckNumberConstant(Node* n, double expected) {
     NumberMatcher m(n);
     CHECK_EQ(IrOpcode::kNumberConstant, n->opcode());
     CHECK(m.HasValue());
     CheckDoubleEq(expected, m.Value());
   }
@@ skipping 461 matching lines @@
   r.CheckTypeError(kRepWord32 | kTypeUint32, kRepWord64);
 
   for (size_t i = 0; i < arraysize(all_reps); i++) {
     for (size_t j = 0; j < arraysize(all_reps); j++) {
       if (i == j) continue;
       // Only a single from representation is allowed.
       r.CheckTypeError(all_reps[i] | all_reps[j], kRepTagged);
     }
   }
 }