Enable do not allow default action for untrusted events.

third_party/WebKit/LayoutTests/fast/events/simulated-key-state.html

-<p>This tests that modifier keys are propagated to the fake mouse event created when you press return and a link has focus.</p>
-<p>If the test succeeds, you should see six "PASS" messages below.</p>
-<p>This is the <a id="link" href="#" onclick="checkKeyState(event)" onmousedown="checkKeyState(event)" onmouseuup="checkKeyState(event)">link</a> used for testing.</p>
-<pre id="console">
-</pre>
-<script>
-
-if (window.testRunner)
-    testRunner.dumpAsText();
-
-var link = document.getElementById("link");
-link.focus();
-
-var expectedCtrl;
-var expectedAlt;
-var expectedShift;
-var expectedMeta;
-
-function test(ctrlKey, altKey, shiftKey, metaKey)
-{
-    expectedCtrl = ctrlKey;
-    expectedAlt = altKey;
-    expectedShift = shiftKey;
-    expectedMeta = metaKey;
-    var event = new KeyboardEvent("keydown", {bubbles: true, cancelable: true, view: document.defaultView, key: "Enter", ctrlKey: ctrlKey, altKey: altKey, shiftKey: shiftKey, metaKey: metaKey});
-    link.dispatchEvent(event);
-}
-
-function checkKeyState(event)
-{
-    if (event.ctrlKey == expectedCtrl && event.altKey == expectedAlt && event.shiftKey == expectedShift && event.metaKey == expectedMeta)
-        document.getElementById("console").innerHTML += "PASS: " + event.type + " event had all the right key state.\n";
-    else
-        document.getElementById("console").innerHTML += "FAIL: " + event.type + " event did not have the right key state.\n";
-}
-
-test(false, false, false, false);
-test(true, false, false, false);
-test(false, true, false, false);
-test(false, false, true, false);
-test(false, false, false, true);
-test(true, true, true, true);
-
-link.blur();
-
-</script>