--- a/caps/nsScriptSecurityManager.cpp
+++ b/caps/nsScriptSecurityManager.cpp
@@ -683,16 +683,25 @@ nsScriptSecurityManager::CheckLoadURIWit
     else if (sViewSourceReachableFromInner &&
              sourceScheme.EqualsIgnoreCase(targetScheme.get()) &&
              NS_SUCCEEDED(aTargetURI->SchemeIs("view-source", &targetIsViewSource)) &&
              targetIsViewSource)
     {
         // exception for foo: linking to view-source:foo for reftests...
         return NS_OK;
     }
+    else if (sourceScheme.EqualsIgnoreCase("file") &&
+             targetScheme.EqualsIgnoreCase("moz-icon"))
+    {
+        // exception for file: linking to moz-icon://.ext?size=...
+        // Note that because targetScheme is the base (innermost) URI scheme,
+        // this does NOT allow file -> moz-icon:file:///... links.
+        // This is intentional.
+        return NS_OK;
+    }
 
     // Check for webextension
     rv = NS_URIChainHasFlags(aTargetURI,
                              nsIProtocolHandler::URI_LOADABLE_BY_EXTENSIONS,
                              &hasFlags);
     NS_ENSURE_SUCCESS(rv, rv);
 
     if (hasFlags && BasePrincipal::Cast(aPrincipal)->AddonPolicy()) {
@@ -832,22 +841,16 @@ nsScriptSecurityManager::CheckLoadURIFla
     // Check for chrome target URI
     bool hasFlags = false;
     rv = NS_URIChainHasFlags(aTargetBaseURI,
                              nsIProtocolHandler::URI_IS_UI_RESOURCE,
                              &hasFlags);
     NS_ENSURE_SUCCESS(rv, rv);
     if (hasFlags) {
         if (aFlags & nsIScriptSecurityManager::ALLOW_CHROME) {
-            // For now, don't change behavior for moz-icon:// and just allow it.
-            if (!targetScheme.EqualsLiteral("chrome")
-                    && !targetScheme.EqualsLiteral("resource")) {
-                return NS_OK;
-            }
-
             // Allow a URI_IS_UI_RESOURCE source to link to a URI_IS_UI_RESOURCE
             // target if ALLOW_CHROME is set.
             //
             // ALLOW_CHROME is a flag that we pass on all loads _except_ docshell
             // loads (since docshell loads run the loaded content with its origin
             // principal). So we're effectively allowing resource://, chrome://,
             // and moz-icon:// source URIs to load resource://, chrome://, and
             // moz-icon:// files, so long as they're not loading it as a document.

--- a/dom/security/test/mixedcontentblocker/file_main_bug803225.html
+++ b/dom/security/test/mixedcontentblocker/file_main_bug803225.html
@@ -13,17 +13,16 @@ https://bugzilla.mozilla.org/show_bug.cg
 <div id="testContent"></div>
 
 <!-- Test additional schemes the Mixed Content Blocker should not block
      "about" protocol URIs that are URI_SAFE_FOR_UNTRUSTED_CONTENT (moz-safe-about; see nsAboutProtocolHandler::NewURI
      "data",
      "javascript",
      "mailto",
      "resource",
-     "moz-icon",
      "wss"
 -->
 
 <script>
 
   //For tests that require setTimeout, set the timeout interval
   var TIMEOUT_INTERVAL = 100;
 
@@ -65,52 +64,41 @@ https://bugzilla.mozilla.org/show_bug.cg
     parent.postMessage({"test": "resource", "msg": "resource with resource protocol loaded"}, "http://mochi.test:8888");
   }
   resource_script.onerror = function() {
     parent.postMessage({"test": "resource", "msg": "resource with resource protocol did not load"}, "http://mochi.test:8888");
   }
 
   testContent.appendChild(resource_script);
 
-  // Test 4: moz-icon within an img tag
-  var image=document.createElement("img");
-  image.src = "moz-icon://dummy.exe?size=16";
-  image.onload = function() {
-    parent.postMessage({"test": "mozicon", "msg": "resource with mozicon protocol loaded"}, "http://mochi.test:8888");
-  }
-  image.onerror = function() {
-    parent.postMessage({"test": "mozicon", "msg": "resource with mozicon protocol did not load"}, "http://mochi.test:8888");
-  }
-  // We don't need to append the image to the document. Doing so causes the image test to run twice.
-
-  // Test 5: about unsafe protocol within an iframe
+  // Test 4: about unsafe protocol within an iframe
   var unsafe_about_frame = document.createElement("iframe");
   unsafe_about_frame.src = "about:config";
   unsafe_about_frame.name = "unsafe_about_protocol";
   unsafe_about_frame.onload = function() {
     parent.postMessage({"test": "unsafe_about", "msg": "resource with unsafe about protocol loaded"}, "http://mochi.test:8888");
   }
   unsafe_about_frame.onerror = function() {
     parent.postMessage({"test": "unsafe_about", "msg": "resource with unsafe about protocol did not load"}, "http://mochi.test:8888");
   }
   testContent.appendChild(unsafe_about_frame);
 
-  // Test 6: data protocol within a script tag
+  // Test 5: data protocol within a script tag
   var x = 2;
   var newscript = document.createElement("script");
   newscript.src= "data:text/javascript,var x = 4;";
   newscript.onload = function() {
     parent.postMessage({"test": "data_protocol", "msg": "resource with data protocol loaded"}, "http://mochi.test:8888");
   }
   newscript.onerror = function() {
     parent.postMessage({"test": "data_protocol", "msg": "resource with data protocol did not load"}, "http://mochi.test:8888");
   }
   testContent.appendChild(newscript);
 
-  // Test 7: mailto protocol
+  // Test 6: mailto protocol
   let mm = SpecialPowers.loadChromeScript(function launchHandler() {
     var { classes: Cc, interfaces: Ci } = Components;
     var ioService = Cc["@mozilla.org/network/io-service;1"].
                       getService(Ci.nsIIOService);
 
     var webHandler = Cc["@mozilla.org/uriloader/web-handler-app;1"].
                        createInstance(Ci.nsIWebHandlerApp);
     webHandler.name = "Web Handler";
@@ -155,17 +143,17 @@ https://bugzilla.mozilla.org/show_bug.cg
     if(!mailto) {
       //There is no onerror event associated with the WebHandler, and hence we need a setTimeout to check the status
       setTimeout(mailtoProtocolStatus, TIMEOUT_INTERVAL);
     }
   }
 
   mailtoProtocolStatus();
 
-  // Test 8: wss protocol
+  // Test 7: wss protocol
   var wss;
   wss = new WebSocket("wss://example.com/tests/dom/security/test/mixedcontentblocker/file_main_bug803225_websocket");
 
   var status_wss = "started";
   wss.onopen = function(e) {
      status_wss = "opened";
      wss.close();
   }

--- a/dom/security/test/mixedcontentblocker/test_bug803225.html
+++ b/dom/security/test/mixedcontentblocker/test_bug803225.html
@@ -31,17 +31,16 @@ https://bugzilla.mozilla.org/show_bug.cg
       counter++;
       callback();
     });
   }
 
   var testsToRun = {
     /* https - Tests already run as part of bug 62178. */
     about: false,
-    mozicon: false,
     resource: false,
     unsafe_about: false,
     data_protocol: false,
     javascript: false,
     mailto: false,
     wss: false,
   };
 
@@ -95,21 +94,16 @@ https://bugzilla.mozilla.org/show_bug.cg
         testsToRun["about"] = true;
         break;
 
       case "resource":
         ok(event.data.msg == "resource with resource protocol loaded", "resource with resource protocol did not load");
         testsToRun["resource"] = true;
         break;
 
-      case "mozicon":
-        ok(event.data.msg == "resource with mozicon protocol loaded", "resource with mozicon protocol did not load");
-        testsToRun["mozicon"] = true;
-        break;
-
       case "unsafe_about":
         // This one should not load
         ok(event.data.msg == "resource with unsafe about protocol did not load", "resource with unsafe about protocol loaded");
         testsToRun["unsafe_about"] = true;
         break;
 
       case "data_protocol":
         ok(event.data.msg == "resource with data protocol loaded", "resource with data protocol did not load");

--- a/image/test/reftest/downscaling/reftest.list
+++ b/image/test/reftest/downscaling/reftest.list
@@ -82,17 +82,19 @@ fuzzy(20,999) != downscale-2d.html?203,5
 fuzzy(20,999) != downscale-2e.html?203,52,bottom about:blank
 
 fuzzy(20,999) != downscale-2a.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2b.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2c.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2d.html?205,53,bottom about:blank
 fuzzy(20,999) fails-if(OSX>=1008&&!skiaContent) != downscale-2e.html?205,53,bottom about:blank
 
-fuzzy(71,3391) skip-if(/^Linux\x20i686/.test(http.oscpu)) == downscale-moz-icon-1.html downscale-moz-icon-1-ref.html # linux32 timeout, bug 1328771
+# Skip on Android because it runs reftests via http, and moz-icon isn't
+# accessible from http/https origins anymore.
+fuzzy(71,3391) skip-if(Android||/^Linux\x20i686/.test(http.oscpu)) == downscale-moz-icon-1.html downscale-moz-icon-1-ref.html # linux32 timeout, bug 1328771
 
 == downscale-png.html?16,16,interlaced downscale-png.html?16,16,normal
 == downscale-png.html?24,24,interlaced downscale-png.html?24,24,normal
 
 # Non-transparent and transparent ICO images
 == downscale-16px.html?ff-0RGB.ico downscale-16px.html?ff-0RGB.png
 fuzzy(1,1) == downscale-16px.html?ff-ARGB.ico downscale-16px.html?ff-ARGB.png
 
@@ -166,17 +168,19 @@ fuzzy(20,999) != downscale-2f.html?203,5
 fuzzy(20,999) != downscale-2a.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2b.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2c.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2d.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2e.html?205,53,bottom about:blank
 fuzzy(20,999) != downscale-2f.html?205,53,bottom about:blank
 
 # Skip on WinXP with skia content
-fuzzy(77,4439) fails-if(/^Windows\x20NT\x205\.1/.test(http.oscpu)) skip-if(/^Linux\x20i686/.test(http.oscpu)) == downscale-moz-icon-1.html downscale-moz-icon-1-ref.html # linux32 timeout, bug 1328771
+# Skip on Android because it runs reftests via http, and moz-icon isn't
+# accessible from http/https origins anymore.
+fuzzy(77,4439) fails-if(/^Windows\x20NT\x205\.1/.test(http.oscpu)) skip-if(Android||/^Linux\x20i686/.test(http.oscpu)) == downscale-moz-icon-1.html downscale-moz-icon-1-ref.html # linux32 timeout, bug 1328771
 
 == downscale-png.html?16,16,interlaced downscale-png.html?16,16,normal
 == downscale-png.html?24,24,interlaced downscale-png.html?24,24,normal
 
 # Non-transparent and transparent ICO images
 fuzzy(1,3) == downscale-16px.html?ff-0RGB.ico downscale-16px.html?ff-0RGB.png
 fuzzy(3,32) == downscale-16px.html?ff-ARGB.ico downscale-16px.html?ff-ARGB.png