Block modal dialogs inside sandboxes.

LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html

Index: LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html
diff --git a/LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html b/LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html
index 8239934b379cbb99bdfce7cd5de513c472958aa5..9f1e6cc902b6178ab6b11cc3a367ced904622ed4 100644
--- a/LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html
+++ b/LayoutTests/fast/forms/autofocus-in-sandbox-with-allow-scripts.html
@@ -7,4 +7,4 @@ if (window.testRunner) {
 This test passes if the activeElement is the input element rather than the body
 (which it would be if the sandbox didn't allow autofocus although allow-scripts flag is set).
 <iframe sandbox="allow-scripts"
-    src="data:text/html,<input autofocus onfocus='alert(document.activeElement.tagName); testRunner.notifyDone();'>"></iframe>
+    src="data:text/html,<input autofocus onfocus='console.log(document.activeElement.tagName); testRunner.notifyDone();'>"></iframe>