Add a MathFloor stub generated with TurboFan

src/runtime/runtime-array.cc

Index: src/runtime/runtime-array.cc
diff --git a/src/runtime/runtime-array.cc b/src/runtime/runtime-array.cc
index 34f873512506f9fca64dde84fdc21c3ce318aaad..49cbc5fd00da600a25ec978f8b67535e5b5509bc 100644
--- a/src/runtime/runtime-array.cc
+++ b/src/runtime/runtime-array.cc
@@ -54,6 +54,26 @@ RUNTIME_FUNCTION(Runtime_SpecialArrayFunctions) {
 }
 
 
+RUNTIME_FUNCTION(Runtime_FixedArrayGet) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 2);
+  CONVERT_ARG_CHECKED(FixedArray, object, 0);
+  CONVERT_SMI_ARG_CHECKED(index, 1);
+  return object->get(index);
+}
+
+
+RUNTIME_FUNCTION(Runtime_FixedArraySet) {
+  SealHandleScope shs(isolate);
+  DCHECK(args.length() == 3);
+  CONVERT_ARG_CHECKED(FixedArray, object, 0);
+  CONVERT_SMI_ARG_CHECKED(index, 1);
+  CONVERT_ARG_CHECKED(Object, value, 2);
+  object->set(index, value);
+  return isolate->heap()->undefined_value();
+}
+
+
 RUNTIME_FUNCTION(Runtime_TransitionElementsKind) {
   HandleScope scope(isolate);
   RUNTIME_ASSERT(args.length() == 2);