Introduce v8::Exception::GetMessage to find location of an error object.

src/isolate.h

Index: src/isolate.h
diff --git a/src/isolate.h b/src/isolate.h
index 7944d0e96370bd830373ca739612efcf33588d84..7e50929ebca31e56698f660b15ea791d5b81924b 100644
--- a/src/isolate.h
+++ b/src/isolate.h
@@ -801,6 +801,11 @@ class Isolate {
   // Attempts to compute the current source location, storing the
   // result in the target out parameter.
   void ComputeLocation(MessageLocation* target);
+  void ComputeLocationFromStackTrace(MessageLocation* target,
+                                     Handle<Object> exception);
+
+  Handle<JSMessageObject> CreateMessage(Handle<Object> exception,
+                                        MessageLocation* location);
 
   // Out of resource exception helpers.
   Object* StackOverflow();
@@ -1201,9 +1206,6 @@ class Isolate {
   // then return true.
   bool PropagatePendingExceptionToExternalTryCatch();
 
-  Handle<JSMessageObject> CreateMessage(Handle<Object> exception,
-                                        MessageLocation* location);
-
   // Traverse prototype chain to find out whether the object is derived from
   // the Error object.
   bool IsErrorObject(Handle<Object> obj);