Teach the background parser to ignore certain elements inside '<select>'.
'HTMLTreeBuilderSimulator' doesn't currently understand that we shouldn't
hop into PLAINTEXTState or RAWTEXTState inside '<select>' elements. This
has the unfortunate side-effect of enabling dangling markup injection
attacks that exfiltrate data via '<select><option><plaintext>' and etc.
This patch ensures that `<select>` behaves as specified, matching Safari,
Firefox, and Edge's behavior.
Thanks to @zcorpan for pointing out Blink's error in the thread ad
(cherry picked from commit 8150200aff6ad60b092fd2ddb7eddcb6d0cc13df)
Review-Url: https://codereview.chromium.org/2630253002 .
3 files changed