Backout merge, a=backing out changeset tried for b7 blocker

dom/base/nsJSEnvironment.cpp

@@ -1238,9 +1238,6 @@ nsJSContext::JSOptionChangedCallback(const char *pref, void *data)
     }
   }    
 
-  if (!chromeWindow)
-    newDefaultJSOptions |= JSOPTION_ROPES;
-
   if (useTraceJIT)
     newDefaultJSOptions |= JSOPTION_JIT;
   else

js/src/jsapi.h

@@ -916,8 +916,6 @@ JS_StringToVersion(const char *string);
 
 #define JSOPTION_METHODJIT      JS_BIT(14)      /* Whole-method JIT. */
 #define JSOPTION_PROFILING      JS_BIT(15)      /* Profiler to make tracer/methodjit choices. */
-#define JSOPTION_ROPES          JS_BIT(16)      /* Enable rope optimization for
-                                                 * string concat. */
 
 extern JS_PUBLIC_API(uint32)
 JS_GetOptions(JSContext *cx);

js/src/jsstr.cpp

@@ -268,8 +268,6 @@ FinishConcat(JSContext *cx, bool usingLeft, bool usingRight,
         left->convertToInteriorNode(res);
     if (usingRight)
         right->convertToInteriorNode(res);
-    if (!JS_HAS_OPTION(cx, JSOPTION_ROPES))
-        res->flatten();
     return res;
 }
 

js/src/shell/js.cpp

@@ -5436,7 +5436,7 @@ main(int argc, char **argv, char **envp)
     if (!cx)
         return 1;
 
-    JS_SetOptions(cx, JS_GetOptions(cx) | JSOPTION_ANONFUNFIX | JSOPTION_ROPES);
+    JS_SetOptions(cx, JS_GetOptions(cx) | JSOPTION_ANONFUNFIX);
     JS_SetGCParameterForThread(cx, JSGC_MAX_CODE_CACHE_BYTES, 16 * 1024 * 1024);
 
     result = Shell(cx, argc, argv, envp);