[builtins] Introduce proper Float64Tan operator.

src/runtime/runtime-test.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/deoptimizer.h"
 #include "src/frames-inl.h"
 #include "src/full-codegen/full-codegen.h"
 #include "src/isolate-inl.h"
 #include "src/snapshot/natives.h"
 
 namespace v8 {
 namespace internal {
 
+RUNTIME_FUNCTION(Runtime_ConstructDouble) {
+  HandleScope scope(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_NUMBER_CHECKED(uint32_t, hi, Uint32, args[0]);
+  CONVERT_NUMBER_CHECKED(uint32_t, lo, Uint32, args[1]);
+  uint64_t result = (static_cast<uint64_t>(hi) << 32) | lo;
+  return *isolate->factory()->NewNumber(uint64_to_double(result));
+}
+
 RUNTIME_FUNCTION(Runtime_DeoptimizeFunction) {
   HandleScope scope(isolate);
   DCHECK(args.length() == 1);
 
   // This function is used by fuzzers to get coverage in compiler.
   // Ignore calls on non-function objects to avoid runtime errors.
   CONVERT_ARG_HANDLE_CHECKED(Object, function_object, 0);
   // If it is not a JSFunction, just return.
   if (!function_object->IsJSFunction()) {
     return isolate->heap()->undefined_value();
@@ skipping 531 matching lines @@
 
 RUNTIME_FUNCTION(Runtime_SpeciesProtector) {
   SealHandleScope shs(isolate);
   DCHECK_EQ(0, args.length());
   return isolate->heap()->ToBoolean(isolate->IsArraySpeciesLookupChainIntact());
 }
 
 
 }  // namespace internal
 }  // namespace v8