diff --git a/layout/generic/test/file_SlowPage.sjs b/layout/generic/test/file_SlowPage.sjs
new file mode 100644
index 000000000000..b9a9ca251524
--- /dev/null
+++ b/layout/generic/test/file_SlowPage.sjs
@@ -0,0 +1,41 @@
+"use strict";
+
+const Cc = Components.classes;
+const Ci = Components.interfaces;
+
+let timer;
+
+const DELAY_MS = 5000;
+
+function handleRequest(request, response) {
+  response.processAsync();
+
+  response.setHeader("Content-Type", "text/html", false);
+  
+  // Include paint_listener.js so that we can call waitForAllPaintsFlushed
+  // on the window in which this is opened.
+  response.write("<script type=\"text/javascript\" src=\"/tests/SimpleTest/paint_listener.js\"></script>");
+  
+  // Allow the opening window to react to loading being complete.
+  response.write("<body onload=\"window.opener.fullyLoaded()\">");
+
+  // Send half of the content.
+  for (var i = 0; i < 100; ++i) {
+    response.write("<p>Some text.</p>");
+  }
+  
+  // Allow the opening window to react to being partially loaded.
+  response.write("<script>window.opener.partiallyLoaded();</script>");
+
+  // Wait for 5 seconds, then send the rest of the content.
+  timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+  timer.init(() => {
+    
+    for (var i = 0; i < 100; ++i) {
+      response.write("<p>Some text.</p>");
+    }
+    response.write("</body>");
+    
+    response.finish();
+  }, DELAY_MS, Ci.nsITimer.TYPE_ONE_SHOT);
+}
diff --git a/layout/generic/test/mochitest.ini b/layout/generic/test/mochitest.ini
index 934ffc8a4461..1cb630003892 100644
--- a/layout/generic/test/mochitest.ini
+++ b/layout/generic/test/mochitest.ini
@@ -15,6 +15,7 @@ support-files =
   file_IconTestServer.sjs
   file_LoadingImageReference.png
   file_SlowImage.sjs
+  file_SlowPage.sjs
   bug1174521.html
 
 [test_bug240933.html]
@@ -136,5 +137,6 @@ support-files = selection_expanding_xbl.xml
 support-files = file_taintedfilters_feDisplacementMap-tainted-1.svg file_taintedfilters_feDisplacementMap-tainted-2.svg file_taintedfilters_feDisplacementMap-tainted-3.svg file_taintedfilters_feDisplacementMap-tainted-ref.svg file_taintedfilters_feDisplacementMap-untainted-ref.svg file_taintedfilters_feDisplacementMap-untainted-1.svg file_taintedfilters_feDisplacementMap-untainted-2.svg file_taintedfilters_red-flood-for-feImage-cors.svg file_taintedfilters_red-flood-for-feImage-cors.svg^headers^ file_taintedfilters_red-flood-for-feImage.svg
 [test_scroll_position_restore.html]
 support-files = file_scroll_position_restore.html
+[test_scroll_position_restore_after_stop.html]
 [test_scroll_animation_restore.html]
 [test_scroll_position_iframe.html]
diff --git a/layout/generic/test/test_scroll_position_restore_after_stop.html b/layout/generic/test/test_scroll_position_restore_after_stop.html
new file mode 100644
index 000000000000..2e62cfc01f66
--- /dev/null
+++ b/layout/generic/test/test_scroll_position_restore_after_stop.html
@@ -0,0 +1,76 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=1312697
+-->
+<head>
+  <meta charset="utf-8">
+  <title>Test for Bug 1312697</title>
+  <script type="application/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <script type="text/javascript" src="/tests/SimpleTest/paint_listener.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<a target="_blank" href="https://bugzilla.mozilla.org/show_bug.cgi?id=1312697">Mozilla Bug 1312697</a>
+<p id="display"></p>
+<script>
+SimpleTest.waitForExplicitFinish();
+
+var loadCount = 0;
+var childWin = window.open('file_SlowPage.sjs', '_blank');
+var targetPos = 0;
+
+// Called by the page in the child window when it's halfway loaded.
+function partiallyLoaded() {
+  if (loadCount == 1) {
+    // Halfway through the first reload, stop loading.
+    childWin.stop();
+    
+    // Force a reflow in the stopped state. This triggers the buggy behaviour. 
+    var newNode = childWin.document.createElement('p');
+    newNode.innerHTML = "Added text.";
+    childWin.document.body.insertBefore(newNode, childWin.document.body.childNodes[0]);
+    
+    childWin.waitForAllPaintsFlushed(function() {
+      // Since we're only partially loaded, we should not have been able to
+      // reach the target scroll position.
+      ok(childWin.scrollY < targetPos, "Expected page to not be fully loaded");
+      
+      // Now re-load again. Continue reading in fullyLoaded(), the 
+      // 'loadCount == 2' case.
+      loadCount++;
+      childWin.location.reload();
+    });
+  }
+}
+
+// Called by the page in the child window when it's fully loaded.
+function fullyLoaded() {
+  if (loadCount == 0) {
+    // Scroll to a target position near the end of the page (past the
+    // half-way point.)
+    targetPos = childWin.scrollMaxY - 100;
+    childWin.scrollTo(0, targetPos);
+    childWin.waitForAllPaintsFlushed(function() {
+      ok(childWin.scrollY == targetPos, "Expected page to have scrolled");
+      
+      // Reload the page.
+      loadCount++;
+      childWin.location.reload();
+      
+      // Next, we'll get into partiallyLoaded(). Read on there.
+    });
+  } else if (loadCount == 2) {
+    // After the second reload is complete, check that the initial target
+    // position was remembered and scrolled to.
+    childWin.waitForAllPaintsFlushed(function() {
+      ok(childWin.scrollY == targetPos, "Expected page to have scrolled to target position");
+      childWin.close();
+      SimpleTest.finish();
+    });
+  }
+}
+
+</script>
+</body>
+</html>
