From a5b58310970ca3c1dae92d0255202148a40999e0 Mon Sep 17 00:00:00 2001
From: Sebastian Hengst <archaeopteryx@coole-files.de>
Date: Sat, 22 Jul 2017 11:08:53 +0200
Subject: [PATCH] Backed out changeset da7ad37975f1 (bug 1377016) on suspicion
 of frequently asserting at dom/script/ScriptLoader.cpp:649 during wpt
 instantiation-error-2.html. r=backout

---
 js/src/jscompartment.cpp | 21 +++++++--------------
 1 file changed, 7 insertions(+), 14 deletions(-)

diff --git a/js/src/jscompartment.cpp b/js/src/jscompartment.cpp
index 5ba99259de63..79b0377d0b55 100644
--- a/js/src/jscompartment.cpp
+++ b/js/src/jscompartment.cpp
@@ -569,13 +569,10 @@ JSCompartment::getOrCreateNonSyntacticLexicalEnvironment(JSContext* cx, HandleOb
             return nullptr;
     }
 
-    // If a wrapped WithEnvironmentObject was passed in, unwrap it, as we may
-    // be creating different WithEnvironmentObject wrappers each time.
-    RootedObject key(cx, enclosing);
-    if (enclosing->is<WithEnvironmentObject>()) {
-        MOZ_ASSERT(!enclosing->as<WithEnvironmentObject>().isSyntactic());
-        key = &enclosing->as<WithEnvironmentObject>().object();
-    }
+    // The key is the unwrapped dynamic scope, as we may be creating different
+    // WithEnvironmentObject wrappers each time.
+    MOZ_ASSERT(!enclosing->as<WithEnvironmentObject>().isSyntactic());
+    RootedObject key(cx, &enclosing->as<WithEnvironmentObject>().object());
     RootedObject lexicalEnv(cx, nonSyntacticLexicalEnvironments_->lookup(key));
 
     if (!lexicalEnv) {
@@ -594,13 +591,9 @@ JSCompartment::getNonSyntacticLexicalEnvironment(JSObject* enclosing) const
 {
     if (!nonSyntacticLexicalEnvironments_)
         return nullptr;
-    // If a wrapped WithEnvironmentObject was passed in, unwrap it as in
-    // getOrCreateNonSyntacticLexicalEnvironment.
-    JSObject* key = enclosing;
-    if (enclosing->is<WithEnvironmentObject>()) {
-        MOZ_ASSERT(!enclosing->as<WithEnvironmentObject>().isSyntactic());
-        key = &enclosing->as<WithEnvironmentObject>().object();
-    }
+    if (!enclosing->is<WithEnvironmentObject>())
+        return nullptr;
+    JSObject* key = &enclosing->as<WithEnvironmentObject>().object();
     JSObject* lexicalEnv = nonSyntacticLexicalEnvironments_->lookup(key);
     if (!lexicalEnv)
         return nullptr;