[runtime] Unify and fix the strict equality comparison.

src/objects.cc

 // Copyright 2013 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 <iomanip>
 #include <sstream>
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
@@ skipping 84 matching lines @@
   if (IsSmi()) return Smi::cast(this)->value() != 0;
   if (IsUndefined() || IsNull()) return false;
   if (IsUndetectableObject()) return false;   // Undetectable object is false.
   if (IsString()) return String::cast(this)->length() != 0;
   if (IsHeapNumber()) return HeapNumber::cast(this)->HeapNumberBooleanValue();
   if (IsSimd128Value()) return true;  // Simd value types evaluate to true.
   return true;
 }
 
 
+bool Object::StrictEquals(Object* that) {
+  if (this->IsNumber()) {
+    if (!that->IsNumber()) return false;
+    double const x = this->Number();
+    double const y = that->Number();
+    // Must check explicitly for NaN:s on Windows, but -0 works fine.
+    return x == y && !std::isnan(x) && !std::isnan(y);
+  } else if (this->IsString()) {
+    if (!that->IsString()) return false;
+    return String::cast(this)->Equals(String::cast(that));
+  } else if (this->IsSimd128Value()) {
+    if (!that->IsSimd128Value()) return false;
+    return Simd128Value::cast(this)->Equals(Simd128Value::cast(that));
+  }
+  return this == that;
+}
+
+
 bool Object::IsCallable() const {
   const Object* fun = this;
   while (fun->IsJSFunctionProxy()) {
     fun = JSFunctionProxy::cast(fun)->call_trap();
   }
   return fun->IsJSFunction() ||
          (fun->IsHeapObject() &&
           HeapObject::cast(fun)->map()->has_instance_call_handler());
 }
 
@@ skipping 15584 matching lines @@
   if (cell->value() != *new_value) {
     cell->set_value(*new_value);
     Isolate* isolate = cell->GetIsolate();
     cell->dependent_code()->DeoptimizeDependentCodeGroup(
         isolate, DependentCode::kPropertyCellChangedGroup);
   }
 }
 
 }  // namespace internal
 }  // namespace v8