diff -r 000000000000 -r 6474c204b198 docshell/test/browser/browser_bug941562.js
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/docshell/test/browser/browser_bug941562.js	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,39 @@
+function test() {
+  waitForExplicitFinish();
+
+  var rootDir = "http://mochi.test:8888/browser/docshell/test/browser/";
+  gBrowser.selectedTab = gBrowser.addTab(rootDir + "file_bug941562.html");
+  gBrowser.selectedBrowser.addEventListener("load", afterOpen, true);
+}
+
+function afterOpen(event) {
+  if (event.target != gBrowser.contentDocument) {
+    return;
+  }
+
+  gBrowser.selectedBrowser.removeEventListener("load", afterOpen, true);
+  gBrowser.selectedBrowser.addEventListener("load", afterChangeCharset, true);
+
+  is(gBrowser.contentDocument.documentElement.textContent.indexOf('\u20AC'), 140, "Parent doc should be windows-1252 initially");
+
+  is(gBrowser.contentDocument.getElementsByTagName("iframe")[0].contentDocument.documentElement.textContent.indexOf('\u4E2D'), 77, "Child doc should be HZ-GB-2312 initially");
+
+  BrowserSetForcedCharacterSet("windows-1251");
+}
+  
+function afterChangeCharset(event) {
+  if (event.target != gBrowser.contentDocument) {
+    return;
+  }
+
+  gBrowser.selectedBrowser.removeEventListener("load", afterChangeCharset, true);
+
+  is(gBrowser.contentDocument.documentElement.textContent.indexOf('\u0402'), 140, "Parent doc should decode as windows-1251 subsequently");
+  is(gBrowser.contentDocument.getElementsByTagName("iframe")[0].contentDocument.documentElement.textContent.indexOf('\u4E2D'), 77, "Child doc should decode as HZ-GB-2312 subsequently");  
+
+  is(gBrowser.contentDocument.characterSet, "windows-1251", "Parent doc should report windows-1251 subsequently");
+  is(gBrowser.contentDocument.getElementsByTagName("iframe")[0].contentDocument.characterSet, "HZ-GB-2312", "Child doc should report HZ-GB-2312 subsequently");
+
+  gBrowser.removeCurrentTab();
+  finish();
+}