[es6] Initial steps towards a correct implementation of IsCallable.

src/runtime/runtime-function.cc

Index: src/runtime/runtime-function.cc
diff --git a/src/runtime/runtime-function.cc b/src/runtime/runtime-function.cc
index 31cda72874ee10b31cc7dc7dffdd99f91779d561..1d0668eec185d7b093f9008aa229d939cba33e1b 100644
--- a/src/runtime/runtime-function.cc
+++ b/src/runtime/runtime-function.cc
@@ -21,10 +21,10 @@ RUNTIME_FUNCTION(Runtime_IsSloppyModeFunction) {
   CONVERT_ARG_CHECKED(JSReceiver, callable, 0);
   if (!callable->IsJSFunction()) {
     HandleScope scope(isolate);
-    Handle<Object> delegate;
+    Handle<JSFunction> delegate;
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
-        isolate, delegate, Execution::TryGetFunctionDelegate(
-                               isolate, Handle<JSReceiver>(callable)));
+        isolate, delegate,
+        Execution::GetFunctionDelegate(isolate, Handle<JSReceiver>(callable)));
     callable = JSFunction::cast(*delegate);
   }
   JSFunction* function = JSFunction::cast(callable);
@@ -514,7 +514,7 @@ RUNTIME_FUNCTION(Runtime_NewObjectFromBound) {
   if (!bound_function->IsJSFunction()) {
     ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
         isolate, bound_function,
-        Execution::TryGetConstructorDelegate(isolate, bound_function));
+        Execution::GetConstructorDelegate(isolate, bound_function));
   }
   DCHECK(bound_function->IsJSFunction());
 
@@ -601,7 +601,10 @@ RUNTIME_FUNCTION(Runtime_GetFunctionDelegate) {
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
   RUNTIME_ASSERT(!object->IsJSFunction());
-  return *Execution::GetFunctionDelegate(isolate, object);
+  Handle<JSFunction> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result, Execution::GetFunctionDelegate(isolate, object));
+  return *result;
 }
 
 
@@ -610,7 +613,10 @@ RUNTIME_FUNCTION(Runtime_GetConstructorDelegate) {
   DCHECK(args.length() == 1);
   CONVERT_ARG_HANDLE_CHECKED(Object, object, 0);
   RUNTIME_ASSERT(!object->IsJSFunction());
-  return *Execution::GetConstructorDelegate(isolate, object);
+  Handle<JSFunction> result;
+  ASSIGN_RETURN_FAILURE_ON_EXCEPTION(
+      isolate, result, Execution::GetConstructorDelegate(isolate, object));
+  return *result;
 }