Better handling of broken applet codebase

Better handling of broken applet codebase

A broken codebase would result in using an invalid url as base url in
the KURL constructor and that never results in anything useful (could
even crash). Since HTMLAppletElement is deprecated and badly documented
the goal of this patch is mostly to avoid the known badness and not to
make HTMLAppletElement perfect.

R=fs@opera.com

BUG=374110
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=193633

[Daniel Bratell, 2015-04-13 09:49:16]

Already reviewed in https://codereview.chromium.org/315683002/ but that CL broke
CQ (too old) so here is a new one.

[Mike West, 2015-04-13 09:50:00]

mkwst@chromium.org changed reviewers:
+ mkwst@chromium.org

[Mike West, 2015-04-13 09:50:01]

LGTM.

[Daniel Bratell, 2015-04-13 09:50:34]

The CQ bit was checked by bratell@opera.com

[commit-bot: I haz the power, 2015-04-13 09:50:39]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1079953002/1

[commit-bot: I haz the power, 2015-04-13 12:52:21]

Committed patchset #1 (id:1) as
https://src.chromium.org/viewvc/blink?view=rev&revision=193633