[builtins] Provide Math.floor as TurboFan builtin.

test/cctest/compiler/test-code-stub-assembler.cc

 // Copyright 2015 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/interface-descriptors.h"
 #include "src/isolate.h"
 #include "test/cctest/compiler/function-tester.h"
 
 namespace v8 {
 namespace internal {
@@ skipping 58 matching lines @@
   CHECK_EQ(0.5, Handle<HeapNumber>::cast(result.ToHandleChecked())->value());
 }
 
 
 TEST(SimpleCallRuntime1Arg) {
   Isolate* isolate(CcTest::InitIsolateOnce());
   VoidDescriptor descriptor(isolate);
   CodeStubAssemblerTester m(isolate, descriptor);
   Node* context = m.HeapConstant(Handle<Context>(isolate->native_context()));
   Node* b = m.SmiTag(m.Int32Constant(256));
-  m.Return(m.CallRuntime(Runtime::kMathFloor, context, b));
+  m.Return(m.CallRuntime(Runtime::kRoundNumber, context, b));
   Handle<Code> code = m.GenerateCode();
   FunctionTester ft(descriptor, code);
   MaybeHandle<Object> result = ft.Call();
   CHECK_EQ(256, Handle<Smi>::cast(result.ToHandleChecked())->value());
 }
 
 
 TEST(SimpleTailCallRuntime1Arg) {
   Isolate* isolate(CcTest::InitIsolateOnce());
   VoidDescriptor descriptor(isolate);
   CodeStubAssemblerTester m(isolate, descriptor);
   Node* context = m.HeapConstant(Handle<Context>(isolate->native_context()));
   Node* b = m.SmiTag(m.Int32Constant(256));
-  m.TailCallRuntime(Runtime::kMathFloor, context, b);
+  m.TailCallRuntime(Runtime::kRoundNumber, context, b);
   Handle<Code> code = m.GenerateCode();
   FunctionTester ft(descriptor, code);
   MaybeHandle<Object> result = ft.Call();
   CHECK_EQ(256, Handle<Smi>::cast(result.ToHandleChecked())->value());
 }
 
 
 TEST(SimpleCallRuntime2Arg) {
   Isolate* isolate(CcTest::InitIsolateOnce());
   VoidDescriptor descriptor(isolate);
@@ skipping 253 matching lines @@
   m.Goto(&l2);
   m.Bind(&l2);
   m.Goto(&default_label);
   m.Bind(&default_label);
   USE(m.GenerateCode());
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8