--- a/js/jsd/jsd_scpt.c
+++ b/js/jsd/jsd_scpt.c
@@ -35,16 +35,17 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 /*
  * JavaScript Debugging support - Script support
  */
 
 #include "jsd.h"
+#include "jsfriendapi.h"
 
 /* Comment this out to disable (NT specific) dumping as we go */
 /*
 ** #ifdef DEBUG      
 ** #define JSD_DUMP 1
 ** #endif            
 */
 
@@ -499,17 +500,19 @@ jsd_GetScriptFilename(JSDContext* jsdc, 
 JSString*
 jsd_GetScriptFunctionName(JSDContext* jsdc, JSDScript *jsdscript)
 {
     JSString* str;
 
     if( ! jsdscript->function )
         return NULL;
     str = JS_GetFunctionId(jsdscript->function);
-    return str ? str : JS_GetEmptyString(jsdc->jsrt);
+
+    /* For compatibility we return "anonymous", not an empty string here. */
+    return str ? str : JS_GetAnonymousString(jsdc->jsrt);
 }
 
 uintN
 jsd_GetScriptBaseLineNumber(JSDContext* jsdc, JSDScript *jsdscript)
 {
     return jsdscript->lineBase;
 }
 

--- a/js/jsd/jsd_stak.c
+++ b/js/jsd/jsd_stak.c
@@ -35,16 +35,17 @@
  *
  * ***** END LICENSE BLOCK ***** */
 
 /*
  * JavaScript Debugging support - Call stack support
  */
 
 #include "jsd.h"
+#include "jsfriendapi.h"
 
 #ifdef DEBUG
 void JSD_ASSERT_VALID_THREAD_STATE(JSDThreadState* jsdthreadstate)
 {
     JS_ASSERT(jsdthreadstate);
     JS_ASSERT(jsdthreadstate->stackDepth > 0);
 }
 
@@ -364,18 +365,27 @@ jsd_GetNameForStackFrame(JSDContext* jsd
     JSString *rv = NULL;
     
     JSD_LOCK_THREADSTATES(jsdc);
     
     if( jsd_IsValidFrameInThreadState(jsdc, jsdthreadstate, jsdframe) )
     {
         JSFunction *fun = JS_GetFrameFunction (jsdthreadstate->context,
                                                jsdframe->fp);
-        if (fun)
+        if( fun )
+        {
             rv = JS_GetFunctionId (fun);
+
+            /*
+             * For compatibility we return "anonymous", not an empty string
+             * here.
+             */
+            if( !rv )
+                rv = JS_GetAnonymousString(jsdc->jsrt);
+        }
     }
     
     JSD_UNLOCK_THREADSTATES(jsdc);
     return rv;
 }
 
 JSBool
 jsd_IsStackFrameDebugger(JSDContext* jsdc, 

--- a/js/jsd/jsd_val.c
+++ b/js/jsd/jsd_val.c
@@ -36,18 +36,17 @@
  * ***** END LICENSE BLOCK ***** */
 
 /*
  * JavaScript Debugging support - Value and Property support
  */
 
 #include "jsd.h"
 #include "jsapi.h"
-#include "jspubtd.h"
-#include "jsprvtd.h"
+#include "jsfriendapi.h"
 
 #ifdef DEBUG
 void JSD_ASSERT_VALID_VALUE(JSDValue* jsdval)
 {
     JS_ASSERT(jsdval);
     JS_ASSERT(jsdval->nref > 0);
     if(!JS_CLIST_IS_EMPTY(&jsdval->props))
     {
@@ -268,18 +267,20 @@ jsd_GetValueFunctionName(JSDContext* jsd
         exceptionState = JS_SaveExceptionState(cx);
         fun = JS_ValueToFunction(cx, jsdval->val);
         JS_RestoreExceptionState(cx, exceptionState);
         JS_LeaveCrossCompartmentCall(call);
         JS_EndRequest(cx);
         if(!fun)
             return NULL;
         jsdval->funName = JS_GetFunctionId(fun);
+
+        /* For compatibility we return "anonymous", not an empty string here. */
         if (!jsdval->funName)
-            jsdval->funName = JS_GetEmptyString(jsdc->jsrt);
+            jsdval->funName = JS_GetAnonymousString(jsdc->jsrt);
     }
     return jsdval->funName;
 }
 
 /***************************************************************************/
 
 JSDValue*
 jsd_NewValue(JSDContext* jsdc, jsval val)

--- a/js/src/Makefile.in
+++ b/js/src/Makefile.in
@@ -129,27 +129,28 @@ CPPSRCS		= \
 		jsanalyze.cpp \
 		jsapi.cpp \
 		jsarena.cpp \
 		jsarray.cpp \
 		jsatom.cpp \
 		jsbool.cpp \
 		jsclone.cpp \
 		jscntxt.cpp \
+		jscompartment.cpp \
 		jsdate.cpp \
 		jsdbgapi.cpp \
 		jsdhash.cpp \
 		jsdtoa.cpp \
 		jsemit.cpp \
 		jsexn.cpp \
+		jsfriendapi.cpp \
 		jsfun.cpp \
 		jsgc.cpp \
 		jsgcchunk.cpp \
 		jsgcstats.cpp \
-		jscompartment.cpp \
 		jshash.cpp \
 		jsinterp.cpp \
 		jsinvoke.cpp \
 		jsiter.cpp \
 		jslock.cpp \
 		jslog2.cpp \
 		jsmath.cpp \
 		jsnativestack.cpp \
@@ -194,16 +195,17 @@ INSTALLED_HEADERS = \
 		jscntxt.h \
 		jscompat.h \
 		jsdate.h \
 		jsdbgapi.h \
 		jsdhash.h \
 		jsdtoa.h \
 		jsemit.h \
 		jsfun.h \
+		jsfriendapi.h \
 		jsgc.h \
 		jscell.h \
 		jsgcchunk.h \
 		jsgcstats.h \
 		jscompartment.h \
 		jshash.h \
 		jsinterp.h \
 		jsinttypes.h \

new file mode 100644
--- /dev/null
+++ b/js/src/jsfriendapi.cpp
@@ -0,0 +1,48 @@
+/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=4 sw=4 et tw=99:
+ *
+ * ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ * The Original Code is SpiderMonkey code.
+ *
+ * The Initial Developer of the Original Code is
+ *   Mozilla Foundation
+ * Portions created by the Initial Developer are Copyright (C) 2010
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#include "jscntxt.h"
+#include "jsfriendapi.h"
+
+JS_FRIEND_API(JSString *)
+JS_GetAnonymousString(JSRuntime *rt)
+{
+    JS_ASSERT(rt->state == JSRTS_UP);
+    return ATOM_TO_STRING(rt->atomState.anonymousAtom);
+}

new file mode 100644
--- /dev/null
+++ b/js/src/jsfriendapi.h
@@ -0,0 +1,53 @@
+/* -*- Mode: C; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ *
+ * ***** BEGIN LICENSE BLOCK *****
+ * Version: MPL 1.1/GPL 2.0/LGPL 2.1
+ *
+ * The contents of this file are subject to the Mozilla Public License Version
+ * 1.1 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ * http://www.mozilla.org/MPL/
+ *
+ * Software distributed under the License is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
+ * for the specific language governing rights and limitations under the
+ * License.
+ *
+ *
+ * The Original Code is SpiderMonkey code.
+ *
+ * The Initial Developer of the Original Code is
+ * Mozilla Corporation.
+ * Portions created by the Initial Developer are Copyright (C) 2010
+ * the Initial Developer. All Rights Reserved.
+ *
+ * Contributor(s):
+ *
+ * Alternatively, the contents of this file may be used under the terms of
+ * either of the GNU General Public License Version 2 or later (the "GPL"),
+ * or the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
+ * in which case the provisions of the GPL or the LGPL are applicable instead
+ * of those above. If you wish to allow use of your version of this file only
+ * under the terms of either the GPL or the LGPL, and not to allow others to
+ * use your version of this file under the terms of the MPL, indicate your
+ * decision by deleting the provisions above and replace them with the notice
+ * and other provisions required by the GPL or the LGPL. If you do not delete
+ * the provisions above, a recipient may use your version of this file under
+ * the terms of any one of the MPL, the GPL or the LGPL.
+ *
+ * ***** END LICENSE BLOCK ***** */
+
+#ifndef jsfriendapi_h___
+#define jsfriendapi_h___
+
+#include "jspubtd.h"
+#include "jsprvtd.h"
+
+JS_BEGIN_EXTERN_C
+
+extern JS_FRIEND_API(JSString *)
+JS_GetAnonymousString(JSRuntime *rt);
+
+JS_END_EXTERN_C
+
+#endif /* jsfriendapi_h___ */