Apply XSSAuditor to html5 import (i.e. <link rel="import">) tags.

This is a case of included content that we had neglected to filter. 

The complexity of the CL is in granting an exemption to same-origin content, which implies applying the same tests to an href attribute that formerly only applied to src attributes.  But we don't want to give a pass to all href attributes irrespective of tag, so we need more flags.

BUG=421166
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=183552

[Tom Sepez, 2014-10-09 19:29:18]

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

[Tom Sepez, 2014-10-09 19:29:19]

Mike, please review.

[Tom Sepez, 2014-10-09 19:31:02]

https://codereview.chromium.org/644663003/diff/1/Source/core/html/parser/XSSA...
File Source/core/html/parser/XSSAuditor.h (right):

https://codereview.chromium.org/644663003/diff/1/Source/core/html/parser/XSSA...
Source/core/html/parser/XSSAuditor.h:107: bool eraseAttributeIfInjected(const
FilterTokenRequest&, const QualifiedName&, const String& replacementValue =
String(), TruncationKind treatment = NormalAttributeTruncation, HrefRestriction
= ProhibitSameOriginHref);
nit: the existing name "treatment" here adds no value. Maybe remove it before
checking this in.

[Mike West, 2014-10-10 04:05:11]

This LGTM. You're right, though, that it's creeping up towards the edge of being
more complicated than it needs to. This flag is pretty comprehensible, however,
and very self-contained. *shrug* I think it's fine to land.

[Tom Sepez, 2014-10-10 16:35:48]

The CQ bit was checked by tsepez@chromium.org

[commit-bot: I haz the power, 2014-10-10 16:36:15]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/644663003/210001

[commit-bot: I haz the power, 2014-10-10 18:12:50]

Committed patchset #2 (id:210001) as 183552