[Interpreter] Add support for calling runtime functions which return a pair.

src/code-factory.cc

Index: src/code-factory.cc
diff --git a/src/code-factory.cc b/src/code-factory.cc
index 949bf9ab9c9db30155785457c92fbdf1172d87fd..22020605c54ae614696addfe9fadff842529b851 100644
--- a/src/code-factory.cc
+++ b/src/code-factory.cc
@@ -360,12 +360,20 @@ Callable CodeFactory::InterpreterPushArgsAndConstruct(Isolate* isolate) {
 
 // static
 Callable CodeFactory::InterpreterCEntry(Isolate* isolate) {
-  // TODO(rmcilroy): Deal with runtime functions that return two values.
   // Note: If we ever use fpregs in the interpreter then we will need to
   // save fpregs too.
   CEntryStub stub(isolate, 1, kDontSaveFPRegs, kArgvInRegister);
   return Callable(stub.GetCode(), InterpreterCEntryDescriptor(isolate));
 }
 
+
+// static
+Callable CodeFactory::InterpreterCEntryPair(Isolate* isolate) {
+  // Note: If we ever use fpregs in the interpreter then we will need to
+  // save fpregs too.
+  CEntryStub stub(isolate, 2, kDontSaveFPRegs, kArgvInRegister);
+  return Callable(stub.GetCode(), InterpreterCEntryDescriptor(isolate));
+}
+
 }  // namespace internal
 }  // namespace v8