Use an observer to power document-start injection.

Fixes #1565
Refs #1384 (GM_addStyle works at document-start now!)
Refs #1519 (Scripts at document-start run in iframes too now!)

components/greasemonkey.js

@@ -340,7 +340,7 @@ function runScriptInSandbox(code, sandbox, script) {
   return true; // did not need a (function() {...})() enclosure.
 }
 
-function startup() {
+function startup(aService) {
   if (gStartupHasRun) return;
   gStartupHasRun = true;
 
@@ -359,6 +359,10 @@ function startup() {
   loader.loadSubScript("chrome://greasemonkey/content/third-party/mpl-utils.js");
 
   loadGreasemonkeyVersion();
+
+  var observerService = Components.classes['@mozilla.org/observer-service;1']
+     .getService(Components.interfaces.nsIObserverService);
+  observerService.addObserver(aService, 'document-element-inserted', false);
 }
 
 /////////////////////////////////// Service ////////////////////////////////////
@@ -433,7 +437,14 @@ service.prototype.observe = function(aSubject, aTopic, aData) {
   switch (aTopic) {
     case 'app-startup':
     case 'profile-after-change':
-      startup();
+      startup(this);
+      break;
+    case 'document-element-inserted':
+      var doc = aSubject;
+      if (null === doc.location) break;
+      if (!GM_util.isGreasemonkeyable(doc.location.href)) break;
+      var win = doc.defaultView;
+      this.runScripts('document-start', win);
       break;
   }
 };

content/browser.js

@@ -26,20 +26,6 @@ GM_BrowserUI.init = function() {
   window.addEventListener("unload", GM_BrowserUI.chromeUnload, false);
 };
 
-GM_BrowserUI.progressListener = {
-  onLocationChange:function(aBrowser, aProgress, aRequest, aURI) {
-    if (aProgress.isLoadingDocument) {
-      GM_BrowserUI.gmSvc.runScripts(
-          'document-start', aProgress.DOMWindow, window);
-    }
-  },
-  onStateChange:function() { },
-  onProgressChange:function() { },
-  onStatusChange:function() { },
-  onSecurityChange:function() { },
-  onLinkIconAvailable:function() { }
-};
-
 /**
  * The browser XUL has loaded. Find the elements we need and set up our
  * listeners and wrapper objects.
@@ -83,8 +69,6 @@ GM_BrowserUI.chromeLoad = function(e) {
   GM_BrowserUI.gmSvc.config;
 
   GM_BrowserUI.showToolbarButton();
-
-  gBrowser.addTabsProgressListener(GM_BrowserUI.progressListener);
 };
 
 GM_BrowserUI.contentLoad = function(event) {