Change Has* and Get*Attributes to return Maybe<*>, indicating possible exceptions.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index e09f773a97abb56fc83d1d5306dbced5148690f2..a358335fba739c94eeb2d78e725f68e9ec5d4c2f 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -106,15 +106,18 @@ typedef ZoneList<Handle<Object> > ZoneObjectList;
 
 // Macros for MaybeHandle.
 
-#define RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, T)  \
-  do {                                                       \
-    Isolate* __isolate__ = (isolate);                        \
-    if (__isolate__->has_scheduled_exception()) {            \
-      __isolate__->PromoteScheduledException();              \
-      return MaybeHandle<T>();                               \
-    }                                                        \
+#define RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate, value) \
+  do {                                                      \
+    Isolate* __isolate__ = (isolate);                       \
+    if (__isolate__->has_scheduled_exception()) {           \
+      __isolate__->PromoteScheduledException();             \
+      return value;                                         \
+    }                                                       \
   } while (false)
 
+#define RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate, T) \
+  RETURN_VALUE_IF_SCHEDULED_EXCEPTION(isolate, MaybeHandle<T>())
+
 #define ASSIGN_RETURN_ON_EXCEPTION_VALUE(isolate, dst, call, value)  \
   do {                                                               \
     if (!(call).ToHandle(&dst)) {                                    \