Speculative Fix for crash in WebCore::Internals::IsSelectPopupVisible

The possible reason of crash seems to be renderer value being null.

R=tkent@chromium.org
BUG=356128

Review URL: https://codereview.chromium.org/318633002

git-svn-id: svn://svn.chromium.org/blink/trunk@175478 bbb929c8-8fbe-4397-9dbb-9b2b20218538
GeolocationController should use HeapVector instead of PersistentHeapVector

This is a follow-up fix after r175430.
We don't need to use a PersistentHeapVector on a stack.

BUG=340522

Review URL: https://codereview.chromium.org/316823003

git-svn-id: svn://svn.chromium.org/blink/trunk@175479 bbb929c8-8fbe-4397-9dbb-9b2b20218538