[es6] Implement spec compliant ToPrimitive in the runtime.

src/messages.h

Index: src/messages.h
diff --git a/src/messages.h b/src/messages.h
index f08135bb16e17c5db3d713a3514a418f12b44536..532db92471a77780644c419d19ef4cd3bee5f3aa 100644
--- a/src/messages.h
+++ b/src/messages.h
@@ -257,6 +257,7 @@ class CallSite {
     "Offset is outside the bounds of the DataView")                            \
   T(InvalidDataViewLength, "Invalid data view length")                         \
   T(InvalidDataViewOffset, "Start offset is outside the bounds of the buffer") \
+  T(InvalidHint, "Invalid hint: %")                                            \
   T(InvalidLanguageTag, "Invalid language tag: %")                             \
   T(InvalidWeakMapKey, "Invalid value used as weak map key")                   \
   T(InvalidWeakSetValue, "Invalid value used in weak set")                     \