Call JS functions via native context instead of js builtins object.

src/assembler.cc

Index: src/assembler.cc
diff --git a/src/assembler.cc b/src/assembler.cc
index b7550bb79594f04ef715289096030ecb20334802..7f30b8bb5ac673050098b4912d033efcd5000bfd 100644
--- a/src/assembler.cc
+++ b/src/assembler.cc
@@ -980,14 +980,17 @@ ExternalReference::ExternalReference(Builtins::Name name, Isolate* isolate)
   : address_(isolate->builtins()->builtin_address(name)) {}
 
 
-ExternalReference::ExternalReference(Runtime::FunctionId id,
-                                     Isolate* isolate)
-  : address_(Redirect(isolate, Runtime::FunctionForId(id)->entry)) {}
+ExternalReference::ExternalReference(Runtime::FunctionId id, Isolate* isolate)
+    : address_(Redirect(isolate, Runtime::FunctionForId(id)->entry)) {
+  DCHECK_NE(Runtime::CONTEXT, Runtime::FunctionForId(id)->intrinsic_type);
+}
 
 
 ExternalReference::ExternalReference(const Runtime::Function* f,
                                      Isolate* isolate)
-  : address_(Redirect(isolate, f->entry)) {}
+    : address_(Redirect(isolate, f->entry)) {
+  DCHECK_NE(Runtime::CONTEXT, f->intrinsic_type);
+}
 
 
 ExternalReference ExternalReference::isolate_address(Isolate* isolate) {