diff --git a/js/src/jsemit.cpp b/js/src/jsemit.cpp
index 1f865da78738..35691a00061d 100644
--- a/js/src/jsemit.cpp
+++ b/js/src/jsemit.cpp
@@ -2232,18 +2232,8 @@ BindNameToSlot(JSContext *cx, JSCodeGenerator *cg, JSParseNode *pn)
             return JS_TRUE;
         if (level >= JS_DISPLAY_SIZE)
             return JS_TRUE;
-
-        /* FIXME: bug 545575 will make this all better. */
         if (cg->flags & TCF_FUN_HEAVYWEIGHT)
             return JS_TRUE;
-        {
-            JSTreeContext *tc = cg;
-            do {
-                tc = tc->parent;
-                if (tc->flags & TCF_FUN_HEAVYWEIGHT)
-                    return JS_TRUE;
-            } while (tc->staticLevel != level);
-        }
 
         if (FUN_FLAT_CLOSURE(cg->fun)) {
             op = JSOP_GETDSLOT;
diff --git a/js/src/jsparse.cpp b/js/src/jsparse.cpp
index af2a5372b51a..fc4e3607b143 100644
--- a/js/src/jsparse.cpp
+++ b/js/src/jsparse.cpp
@@ -2235,28 +2235,7 @@ Parser::setFunctionKinds(JSFunctionBox *funbox, uint32& tcflags)
                     JSDefinition *lexdep = ALE_DEFN(ale)->resolve();
 
                     if (!lexdep->isFreeVar()) {
-                        uintN lexdepLevel = lexdep->frameLevel();
-                        JS_ASSERT(lexdepLevel <= funbox->level);
-
-                        /* FIXME: bug 545575 will make this all better. */
-                        JSFunctionBox *afunbox = funbox;
-                        do {
-                            /*
-                             * NB: (funbox->tcflags & TCF_FUN_HEAVYWEIGHT) was
-                             * checked first thing, so here we need only check
-                             * after each step up the funbox->parent chain.
-                             *
-                             * As usual if we run out of funboxes we must use
-                             * tcflags to handle the Function constructor case.
-                             */
-                            if ((afunbox->parent ? afunbox->parent->tcflags : tcflags)
-                                & TCF_FUN_HEAVYWEIGHT) {
-                                nupvars = 0;
-                                goto break2;
-                            }
-                            afunbox = afunbox->parent;
-                        } while (afunbox && afunbox->level != lexdepLevel);
-
+                        JS_ASSERT(lexdep->frameLevel() <= funbox->level);
                         ++nupvars;
                         if (lexdep->isAssigned())
                             break;
@@ -2265,7 +2244,6 @@ Parser::setFunctionKinds(JSFunctionBox *funbox, uint32& tcflags)
                 if (!ale)
                     mutation = false;
 
-              break2:
                 if (nupvars == 0) {
                     FUN_METER(onlyfreevar);
                     FUN_SET_KIND(fun, JSFUN_NULL_CLOSURE);
diff --git a/js/src/tests/ecma_3/Function/jstests.list b/js/src/tests/ecma_3/Function/jstests.list
index fee2a4ecc03a..343f20df34df 100644
--- a/js/src/tests/ecma_3/Function/jstests.list
+++ b/js/src/tests/ecma_3/Function/jstests.list
@@ -9,7 +9,6 @@ script regress-137181.js
 script regress-193555.js
 script regress-313570.js
 script regress-49286.js
-script regress-558720.js
 script regress-58274.js
 script regress-85880.js
 script regress-94506.js
diff --git a/js/src/tests/ecma_3/Function/regress-558720.js b/js/src/tests/ecma_3/Function/regress-558720.js
deleted file mode 100644
index 3de0745bd432..000000000000
--- a/js/src/tests/ecma_3/Function/regress-558720.js
+++ /dev/null
@@ -1,23 +0,0 @@
-/*
- * Any copyright is dedicated to the Public Domain.
- * http://creativecommons.org/licenses/publicdomain/
- */
-
-var gTestfile = 'regress-558720.js';
-var BUGNUMBER = 558720;
-var summary = 'bad closure optimization inside "with"';
-var actual;
-var expect;
-
-printBugNumber(BUGNUMBER);
-printStatus(summary);
-
-var a = new Function("a","b","with(a){return(function(){return b})()}");
-var actual = a({b:"green"}) || "red";
-
-eval("function a(a,b){with(a){return(function(){return b})()}}");
-var expect = a({b:"green"}) || "red";
-
-reportCompare(expect, actual, summary);
-
-printStatus("All tests passed!");