Don't allow popups during page unloading times.

Precisely, this disallows them when the event loop's
termination nesting level is nonzero.

This is now part of the spec,
https://html.spec.whatwg.org/#apis-for-creating-and-navigating-browsing-contexts-by-name

> The window open steps, given a string url, a string target, and a string features, are as follows:
> 1. If the event loop's termination nesting level is nonzero, return null.

BUG=844455

Change-Id: I85fb003063f5ed051049c7c263391835421902ac
Reviewed-on: https://chromium-review.googlesource.com/c/1180296
Commit-Queue: Avi Drissman <avi@chromium.org>
Reviewed-by: Nate Chapin <japhet@chromium.org>
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605025}

html/browsers/the-window-object/apis-for-creating-and-navigating-browsing-contexts-by-name/no_window_open_when_term_nesting_level_nonzero.window.js

@@ -0,0 +1,113 @@
+test(function() {
+  var test_window = window.open('', '', 'height=1,width=1');
+  var test_document = test_window.document;
+
+  var frame = test_document.createElement('iframe');
+  test_document.body.appendChild(frame);
+
+  frame.contentWindow.onpagehide = function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during pagehide");
+  };
+  frame.contentDocument.onvisibilitychange = function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during visibilitychange");
+  };
+  frame.contentWindow.onbeforeunload = function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during beforeunload");
+  };
+  frame.contentWindow.onunload = function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during unload");
+  };
+
+  frame.remove();
+}, 'no popups with frame removal');
+
+async_test(function(t) {
+  var test_window = window.open('', '', 'height=1,width=1');
+  var test_document = test_window.document;
+
+  var frame = test_document.createElement('iframe');
+  test_document.body.appendChild(frame);
+
+  frame.contentWindow.onpagehide = t.step_func(function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during pagehide");
+  });
+  frame.contentDocument.onvisibilitychange = t.step_func(function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during visibilitychange");
+  });
+  frame.contentWindow.onbeforeunload = t.step_func(function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during beforeunload");
+  });
+  frame.contentWindow.onunload = t.step_func(function(evt) {
+    assert_equals(frame.contentWindow.open('', '', 'height=1,width=1'), null,
+      "expected no popup during unload");
+  });
+
+  frame.onload = t.step_func_done();
+
+  frame.contentWindow.location.href = "about:blank";
+}, 'no popups with frame navigation');
+
+async_test(function(t) {
+  var test_window = window.open('', '', 'height=1,width=1');
+  var test_document = test_window.document;
+
+  var frame = test_document.createElement('iframe');
+  test_document.body.appendChild(frame);
+
+  frame.contentWindow.onpagehide = t.step_func(function(evt) {
+    assert_equals(test_window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during pagehide");
+  });
+  frame.contentDocument.onvisibilitychange = t.step_func(function(evt) {
+    assert_equals(test_window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during visibilitychange");
+  });
+  frame.contentWindow.onbeforeunload = t.step_func(function(evt) {
+    assert_equals(test_window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during beforeunload");
+  });
+  frame.contentWindow.onunload = t.step_func(function(evt) {
+    assert_equals(test_window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during unload");
+  });
+
+  frame.onload = t.step_func_done();
+
+  frame.contentWindow.location.href = "about:blank";
+}, 'no popups from synchronously reachable window');
+
+async_test(function(t) {
+  var test_window = window.open('', '', 'height=1,width=1');
+  var test_document = test_window.document;
+
+  var frame = test_document.createElement('iframe');
+  test_document.body.appendChild(frame);
+
+  frame.contentWindow.onpagehide = t.step_func(function(evt) {
+    assert_equals(window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during pagehide");
+  });
+  frame.contentDocument.onvisibilitychange = t.step_func(function(evt) {
+    assert_equals(window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during visibilitychange");
+  });
+  frame.contentWindow.onbeforeunload = t.step_func(function(evt) {
+    assert_equals(window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during beforeunload");
+  });
+  frame.contentWindow.onunload = t.step_func(function(evt) {
+    assert_equals(window.open('', '', 'height=1,width=1'), null,
+      "expected no popup during unload");
+  });
+
+  frame.onload = t.step_func_done();
+
+  frame.contentWindow.location.href = "about:blank";
+}, 'no popups from another synchronously reachable window');