diff --git a/content/html/document/src/nsHTMLDocument.cpp b/content/html/document/src/nsHTMLDocument.cpp
index 7a482101fa3a..ab7ea266e4f5 100644
--- a/content/html/document/src/nsHTMLDocument.cpp
+++ b/content/html/document/src/nsHTMLDocument.cpp
@@ -628,14 +628,11 @@ CheckSameOrigin(nsINode* aNode1, nsINode* aNode2)
   NS_PRECONDITION(aNode1, "Null node?");
   NS_PRECONDITION(aNode2, "Null node?");
 
-  nsIScriptSecurityManager* secMan = nsContentUtils::GetSecurityManager();
-  if (!secMan) {
-    return PR_FALSE;
-  }
-
+  PRBool equal;
   return
-    NS_SUCCEEDED(secMan->CheckSameOriginPrincipal(aNode1->NodePrincipal(),
-                                                  aNode2->NodePrincipal()));
+    NS_SUCCEEDED(aNode1->NodePrincipal()->
+                   Equals(aNode2->NodePrincipal(), &equal)) &&
+    equal;
 }
 
 PRBool
@@ -2146,9 +2143,10 @@ nsHTMLDocument::OpenCommon(const nsACString& aContentType, PRBool aReplace)
 
     // If callerPrincipal doesn't match our principal. make sure that
     // SetNewDocument gives us a new inner window and clears our scope.
+    PRBool samePrincipal;
     if (!callerPrincipal ||
-        NS_FAILED(nsContentUtils::GetSecurityManager()->
-          CheckSameOriginPrincipal(callerPrincipal, NodePrincipal()))) {
+        NS_FAILED(callerPrincipal->Equals(NodePrincipal(), &samePrincipal)) ||
+        !samePrincipal) {
       SetIsInitialDocument(PR_FALSE);
     }      
 
@@ -4018,8 +4016,11 @@ nsHTMLDocument::SetDesignMode(const nsAString & aDesignMode)
     rv = secMan->GetSubjectPrincipal(getter_AddRefs(subject));
     NS_ENSURE_SUCCESS(rv, rv);
     if (subject) {
-      rv = secMan->CheckSameOriginPrincipal(subject, NodePrincipal());
+      PRBool subsumes;
+      rv = subject->Subsumes(NodePrincipal(), &subsumes);
       NS_ENSURE_SUCCESS(rv, rv);
+
+      NS_ENSURE_TRUE(subsumes, NS_ERROR_DOM_PROP_ACCESS_DENIED);
     }
   }
 
diff --git a/docshell/base/nsDocShell.cpp b/docshell/base/nsDocShell.cpp
index aed29cf57457..caff39779cd6 100644
--- a/docshell/base/nsDocShell.cpp
+++ b/docshell/base/nsDocShell.cpp
@@ -1025,10 +1025,11 @@ nsDocShell::ValidateOrigin(nsIDocShellTreeItem* aOriginTreeItem,
     nsCOMPtr<nsIDocument> targetDocument(do_QueryInterface(targetDOMDocument));
     NS_ENSURE_TRUE(targetDocument, PR_FALSE);
 
+    PRBool equal;
     return
-        NS_SUCCEEDED(securityManager->
-                     CheckSameOriginPrincipal(originDocument->NodePrincipal(),
-                                              targetDocument->NodePrincipal()));
+        NS_SUCCEEDED(originDocument->NodePrincipal()->
+                       Equals(targetDocument->NodePrincipal(), &equal)) &&
+        equal;
 }
 
 NS_IMETHODIMP
@@ -6209,12 +6210,16 @@ nsDocShell::CheckLoadingPermissions()
         }
 
         // Compare origins
-        sameOrigin =
-            securityManager->CheckSameOriginPrincipal(subjPrincipal, p);
+        PRBool equal;
+        sameOrigin = subjPrincipal->Equals(p, &equal);
         if (NS_SUCCEEDED(sameOrigin)) {
-            // Same origin, permit load
+            if (equal) {
+                // Same origin, permit load
 
-            return sameOrigin;
+                return sameOrigin;
+            }
+
+            sameOrigin = NS_ERROR_DOM_PROP_ACCESS_DENIED;
         }
 
         nsCOMPtr<nsIDocShellTreeItem> tmp;
diff --git a/dom/src/base/nsGlobalWindow.cpp b/dom/src/base/nsGlobalWindow.cpp
index 5a2b11f412a9..c08a99a1e95b 100644
--- a/dom/src/base/nsGlobalWindow.cpp
+++ b/dom/src/base/nsGlobalWindow.cpp
@@ -992,10 +992,10 @@ nsGlobalWindow::WouldReuseInnerWindow(nsIDocument *aNewDocument)
     return PR_TRUE;
   }
 
-  if (nsContentUtils::GetSecurityManager() &&
-      NS_SUCCEEDED(nsContentUtils::GetSecurityManager()->
-        CheckSameOriginPrincipal(mDoc->NodePrincipal(),
-                                 aNewDocument->NodePrincipal()))) {
+  PRBool equal;
+  if (NS_SUCCEEDED(mDoc->NodePrincipal()->Equals(aNewDocument->NodePrincipal(),
+                                                 &equal)) &&
+      equal) {
     // The origin is the same.
     return PR_TRUE;
   }
@@ -1329,10 +1329,10 @@ nsGlobalWindow::SetNewDocument(nsIDocument* aDocument,
   // the existing inner window or the new document is from the same
   // origin as the old document.
   if (!reUseInnerWindow && mNavigator && oldPrincipal) {
-    rv = nsContentUtils::GetSecurityManager()->
-      CheckSameOriginPrincipal(oldPrincipal, aDocument->NodePrincipal());
+    PRBool equal;
+    rv = oldPrincipal->Equals(aDocument->NodePrincipal(), &equal);
 
-    if (NS_FAILED(rv)) {
+    if (NS_FAILED(rv) || !equal) {
       // Different origins.  Release the navigator object so it gets
       // recreated for the new document.  The plugins or mime types
       // arrays may have changed. See bug 150087.
@@ -6566,9 +6566,9 @@ nsGlobalWindow::SetTimeoutOrInterval(nsIScriptTimeoutHandler *aHandler,
   timeout->mScriptHandler = aHandler;
 
   // Get principal of currently executing code, save for execution of timeout.
-  // If either our principals subsume the subject principal, or we're from the
-  // same origin, then use the subject principal. Otherwise, use our principal
-  // to avoid running script in elevated principals.
+  // If our principals subsume the subject principal then use the subject
+  // principal. Otherwise, use our principal to avoid running script in
+  // elevated principals.
 
   nsCOMPtr<nsIPrincipal> subjectPrincipal;
   nsresult rv;
@@ -6583,8 +6583,10 @@ nsGlobalWindow::SetTimeoutOrInterval(nsIScriptTimeoutHandler *aHandler,
   PRBool subsumes = PR_FALSE;
   nsCOMPtr<nsIPrincipal> ourPrincipal = GetPrincipal();
 
-  // Note the direction of this test: We don't allow chrome setTimeouts on
-  // content windows, but we do allow content setTimeouts on chrome windows.
+  // Note the direction of this test: We don't allow setTimeouts running with
+  // chrome privileges on content windows, but we do allow setTimeouts running
+  // with content privileges on chrome windows (where they can't do very much,
+  // of course).
   rv = ourPrincipal->Subsumes(subjectPrincipal, &subsumes);
   if (NS_FAILED(rv)) {
     timeout->Release();
@@ -6595,13 +6597,7 @@ nsGlobalWindow::SetTimeoutOrInterval(nsIScriptTimeoutHandler *aHandler,
   if (subsumes) {
     timeout->mPrincipal = subjectPrincipal;
   } else {
-    // Subsumes does a very strict equality test. Allow sites of the same origin
-    // to set timeouts on each other.
-
-    rv = nsContentUtils::GetSecurityManager()->
-      CheckSameOriginPrincipal(subjectPrincipal, ourPrincipal);
-    timeout->mPrincipal = NS_SUCCEEDED(rv) ? subjectPrincipal : ourPrincipal;
-    rv = NS_OK;
+    timeout->mPrincipal = ourPrincipal;
   }
 
   PRTime delta = (PRTime)realInterval * PR_USEC_PER_MSEC;