[compiler] Introduce initial StrictEqualStub.

src/runtime/runtime-strings.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 "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/conversions-inl.h"
 #include "src/isolate-inl.h"
 #include "src/regexp/jsregexp-inl.h"
@@ skipping 1127 matching lines @@
   if (is_one_byte) {
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, result, isolate->factory()->NewRawOneByteString(length));
   } else {
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, result, isolate->factory()->NewRawTwoByteString(length));
   }
   return *result;
 }
 
-
-RUNTIME_FUNCTION(Runtime_StringEquals) {
+RUNTIME_FUNCTION(Runtime_StringEqual) {
   HandleScope handle_scope(isolate);
-  DCHECK(args.length() == 2);
-
+  DCHECK_EQ(2, args.length());
   CONVERT_ARG_HANDLE_CHECKED(String, x, 0);
   CONVERT_ARG_HANDLE_CHECKED(String, y, 1);
-
-  bool not_equal = !String::Equals(x, y);
-  // This is slightly convoluted because the value that signifies
-  // equality is 0 and inequality is 1 so we have to negate the result
-  // from String::Equals.
-  DCHECK(not_equal == 0 || not_equal == 1);
-  STATIC_ASSERT(EQUAL == 0);
-  STATIC_ASSERT(NOT_EQUAL == 1);
-  return Smi::FromInt(not_equal);
+  return isolate->heap()->ToBoolean(String::Equals(x, y));
 }
 
 
 RUNTIME_FUNCTION(Runtime_FlattenString) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(String, str, 0);
   return *String::Flatten(str);
 }
 
@@ skipping 66 matching lines @@
   SealHandleScope shs(isolate);
   DCHECK(args.length() == 2);
   if (!args[0]->IsString()) return isolate->heap()->undefined_value();
   if (!args[1]->IsNumber()) return isolate->heap()->undefined_value();
   if (std::isinf(args.number_at(1))) return isolate->heap()->nan_value();
   return __RT_impl_Runtime_StringCharCodeAtRT(args, isolate);
 }
 
 }  // namespace internal
 }  // namespace v8