Block modal dialogs inside sandboxes.

LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html

Index: LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html
diff --git a/LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html b/LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html
index 734a415f4fe83854683558622f633bf089ffd2f1..e74ff010781a02ec9281337217d057a6d00dfda8 100644
--- a/LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html
+++ b/LayoutTests/http/tests/security/no-indexeddb-from-sandbox.html
@@ -7,12 +7,12 @@ if (window.testRunner)
          <script>
              try {
                  indexedDB.open('test');
-                 alert('FAIL: indexedDB.open() should throw a SECURITY_ERR in a sandbox.');
+                 console.log('FAIL: indexedDB.open() should throw a SECURITY_ERR in a sandbox.');
              } catch (e) {
                  if (e.code === DOMException.SECURITY_ERR)
-                     alert('PASS: indexedDB.open() threw a SECURITY_ERR!');
+                     console.log('PASS: indexedDB.open() threw a SECURITY_ERR!');
                  else
-                     alert('FAIL: indexedDB.open() threw a ' + e.name);
+                     console.log('FAIL: indexedDB.open() threw a ' + e.name);
              }
          </script>"
      ></iframe>