Can't allocate new stack chunks while on trace (484524, r=brendan).

js/src/jsinterp.cpp

@@ -563,6 +563,9 @@ js_AllocRawStack(JSContext *cx, uintN nslots, void **markp)
 {
     jsval *sp;
 
+    JS_ASSERT(nslots != 0);
+    js_LeaveTrace(cx);
+
     if (!cx->stackPool.first.next) {
         int64 *timestamp;
 

js/src/jsstr.cpp

@@ -1543,8 +1543,6 @@ find_replen(JSContext *cx, ReplaceData *rdata, size_t *sizep)
         void *mark;
         JSBool ok;
 
-        JS_ASSERT_NOT_ON_TRACE(cx);
-
         /*
          * Save the regExpStatics from the current regexp, since they may be
          * clobbered by a RegExp usage in the lambda function.  Note that all