Remove internalSubset from DocumentType

Remove internalSubset from DocumentType

Remove internalSubset from DocumentType, since even though it is being read in MarkupAccumulator it is not being set anywhere, and also it is scheduled to be removed from latest DOM spec.

Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=174043

[rwlbuis, 2014-05-14 15:57:58]

PTAL, it seems safe to remove but may need an Intent to remove? According to the
posted UseCounter data the usage is super low.

[arv (Not doing code reviews), 2014-05-14 16:58:05]

LGTM

The use counter shows 0.0004%

Since it was never set the value was exposed as null to JavaScript. With this
change the value will be undefined (since the property is missing) which is
good.

https://codereview.chromium.org/282823004/diff/1/Source/core/dom/DocumentType...
File Source/core/dom/DocumentType.idl (left):

https://codereview.chromium.org/282823004/diff/1/Source/core/dom/DocumentType...
Source/core/dom/DocumentType.idl:30: [TreatReturnedNullStringAs=Null,
MeasureAs=DocumentTypeInternalSubset] readonly attribute DOMString
internalSubset; // Removed from DOM4.
Can you remove DocumentTypeInternalSubset from UseCounter too?

[rwlbuis, 2014-05-14 17:12:25]

The CQ bit was checked by rob.buis@samsung.com

[commit-bot: I haz the power, 2014-05-14 17:12:33]

CQ is trying da patch. Follow status at
 https://chromium-status.appspot.com/cq/rob.buis@samsung.com/282823004/20001

[commit-bot: I haz the power, 2014-05-14 18:22:03]

FYI, CQ is re-trying this CL (attempt #1).
Please consider checking whether the failures are real,
and report flakes to chrome-troopers@google.com.
The failing builders are:
  mac_blink_rel on tryserver.blink
(http://build.chromium.org/p/tryserver.blink/builders/mac_blink_rel/builds/6704)

[commit-bot: I haz the power, 2014-05-14 18:59:05]

Change committed as 174043