Remove unused GetRootNaN

BUG=v8:6005

Review-Url: https://codereview.chromium.org/2726853006
Cr-Commit-Position: refs/heads/master@{#43531}

src/js/v8natives.js

@@ -11,7 +11,6 @@
 
 var GlobalObject = global.Object;
 var iteratorSymbol = utils.ImportNow("iterator_symbol");
-var NaN = %GetRootNaN();
 var ObjectToString = utils.ImportNow("object_to_string");
 
 // ----------------------------------------------------------------------------

src/runtime/runtime-numbers.cc

@@ -213,13 +213,6 @@ RUNTIME_FUNCTION(Runtime_IsSmi) {
 }
 
 
-RUNTIME_FUNCTION(Runtime_GetRootNaN) {
-  SealHandleScope shs(isolate);
-  DCHECK_EQ(0, args.length());
-  return isolate->heap()->nan_value();
-}
-
-
 RUNTIME_FUNCTION(Runtime_GetHoleNaNUpper) {
   HandleScope scope(isolate);
   DCHECK_EQ(0, args.length());

src/runtime/runtime.h

@@ -371,7 +371,6 @@ namespace internal {
   F(SmiLexicographicCompare, 2, 1)     \
   F(MaxSmi, 0, 1)                      \
   F(IsSmi, 1, 1)                       \
-  F(GetRootNaN, 0, 1)                  \
   F(GetHoleNaNUpper, 0, 1)             \
   F(GetHoleNaNLower, 0, 1)