Bug 375801: Using (void 0) instead of "undefined" in toSource and uneval(), r=mrbkap

js/src/jsatom.c

@@ -338,6 +338,7 @@ js_InitPinnedAtoms(JSContext *cx, JSAtomState *state)
     FROB(toStringAtom,            js_toString_str);
     FROB(toLocaleStringAtom,      js_toLocaleString_str);
     FROB(valueOfAtom,             js_valueOf_str);
+    FROB(void0Atom,               "(void 0)");
 
 #if JS_HAS_XML_SUPPORT
     FROB(etagoAtom,               js_etago_str);

js/src/jsatom.h

@@ -203,6 +203,7 @@ struct JSAtomState {
     JSAtom              *toSourceAtom;
     JSAtom              *toStringAtom;
     JSAtom              *valueOfAtom;
+    JSAtom              *void0Atom;
     JSAtom              *xmlAtom;
 
     /* Less frequently used atoms, pinned lazily by JS_ResolveStandardClass. */

js/src/jsstr.c

@@ -2688,6 +2688,8 @@ js_ValueToSource(JSContext *cx, jsval v)
     JSTempValueRooter tvr;
     JSString *str;
 
+    if (JSVAL_IS_VOID(v))
+        return ATOM_TO_STRING(cx->runtime->atomState.void0Atom);
     if (JSVAL_IS_STRING(v))
         return js_QuoteString(cx, JSVAL_TO_STRING(v), '"');
     if (JSVAL_IS_PRIMITIVE(v)) {