diff --git a/mozilla/dom/public/nsIScriptContext.h b/mozilla/dom/public/nsIScriptContext.h
index 1f162842058..cb0464cc3c1 100644
--- a/mozilla/dom/public/nsIScriptContext.h
+++ b/mozilla/dom/public/nsIScriptContext.h
@@ -326,6 +326,11 @@ public:
    */
   NS_IMETHOD GetProcessingScriptTag(PRBool * aResult) =0;
   NS_IMETHOD SetProcessingScriptTag(PRBool  aResult) =0;
+
+  /**
+   * Tell the context whether or not to GC when destroyed.
+   */
+  NS_IMETHOD SetGCOnDestruction(PRBool aGCOnDestruction) = 0;
 };
 
 #endif // nsIScriptContext_h__
diff --git a/mozilla/dom/src/base/nsGlobalWindow.cpp b/mozilla/dom/src/base/nsGlobalWindow.cpp
index 53060711447..cb005056624 100644
--- a/mozilla/dom/src/base/nsGlobalWindow.cpp
+++ b/mozilla/dom/src/base/nsGlobalWindow.cpp
@@ -193,8 +193,6 @@ GlobalWindowImpl::~GlobalWindowImpl()
 {
   if (!--gRefCnt) {
     NS_IF_RELEASE(gEntropyCollector);
-
-    NS_IF_RELEASE(sXPConnect);
   }
 
   mDocument = nsnull;           // Forces Release
@@ -278,6 +276,19 @@ NS_IMETHODIMP GlobalWindowImpl::SetContext(nsIScriptContext* aContext)
 
   mContext = aContext;
 
+  if (mContext) {
+    nsCOMPtr<nsIDOMWindow> parent;
+    GetParent(getter_AddRefs(parent));
+
+    if (parent && parent != NS_STATIC_CAST(nsIDOMWindow *, this)) {
+      // This window is a [i]frame, don't bother GC'ing when the
+      // frame's context is destroyed since a GC will happen when the
+      // frameset or host document is destroyed anyway.
+
+      mContext->SetGCOnDestruction(PR_FALSE);
+    }
+  }
+
   return NS_OK;
 }
 
diff --git a/mozilla/dom/src/base/nsJSEnvironment.cpp b/mozilla/dom/src/base/nsJSEnvironment.cpp
index e398db27f7a..7020d8c21f9 100644
--- a/mozilla/dom/src/base/nsJSEnvironment.cpp
+++ b/mozilla/dom/src/base/nsJSEnvironment.cpp
@@ -350,7 +350,7 @@ nsJSContext::JSOptionChangedCallback(const char *pref, void *data)
   return 0;
 }
 
-nsJSContext::nsJSContext(JSRuntime *aRuntime)
+nsJSContext::nsJSContext(JSRuntime *aRuntime) : mGCOnDestruction(PR_TRUE)
 {
   NS_INIT_REFCNT();
 
@@ -420,7 +420,7 @@ nsJSContext::~nsJSContext()
   // Let xpconnect destroy the JSContext when it thinks the time is right.
   nsCOMPtr<nsIXPConnect> xpc(do_GetService(nsIXPConnect::GetCID()));
   if (xpc) {
-    xpc->ReleaseJSContext(mContext, PR_FALSE);
+    xpc->ReleaseJSContext(mContext, !mGCOnDestruction);
   } else {
     ::JS_DestroyContext(mContext);
   }
@@ -1496,6 +1496,14 @@ nsJSContext::SetProcessingScriptTag(PRBool aFlag)
   return NS_OK;
 }
 
+NS_IMETHODIMP
+nsJSContext::SetGCOnDestruction(PRBool aGCOnDestruction)
+{
+  mGCOnDestruction = aGCOnDestruction;
+
+  return NS_OK;
+}
+
 NS_IMETHODIMP
 nsJSContext::ScriptExecuted()
 {
diff --git a/mozilla/dom/src/base/nsJSEnvironment.h b/mozilla/dom/src/base/nsJSEnvironment.h
index 62a0e5ba6cc..3d626c7aeed 100644
--- a/mozilla/dom/src/base/nsJSEnvironment.h
+++ b/mozilla/dom/src/base/nsJSEnvironment.h
@@ -124,6 +124,8 @@ public:
   NS_IMETHOD GetProcessingScriptTag(PRBool * aResult);
   NS_IMETHOD SetProcessingScriptTag(PRBool  aResult);
 
+  NS_IMETHOD SetGCOnDestruction(PRBool aGCOnDestruction);
+
   NS_DECL_NSIXPCSCRIPTNOTIFY
 protected:
   nsresult InitClasses();
@@ -142,6 +144,7 @@ private:
 
   PRPackedBool mIsInitialized;
   PRPackedBool mScriptsEnabled;
+  PRPackedBool mGCOnDestruction;
 
   PRUint32 mBranchCallbackCount;
   PRUint32 mDefaultJSOptions;