Implement ParentNode IDL interface

Implement ParentNode IDL interface

http://dom.spec.whatwg.org/#parentnode

This is not a complete implementation of that interface. It is mostly a
refactoring to support

    children
    firstElementChild
    lastElementChild
    childElementCount

on Element, DocumentFragment and Document.

BUG=239159
Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=150240

[arv (Not doing code reviews), 2013-05-09 22:27:37]

Adam, I'm confused by all of these [PerWorldBindings] annotations. What are they
for and when should I use them?

[abarth-chromium, 2013-05-09 22:48:21]

On 2013/05/09 22:27:37, arv wrote:
> Adam, I'm confused by all of these [PerWorldBindings] annotations. What are
they
> for and when should I use them?

They're a performance optimization.  They let us trade binary size (and some
memory) for runtime speed.  The attribute should only be used on extremely hot
DOM APIs, and only if the attribute shows a measurable improvement on a perf
graph.

[abarth-chromium, 2013-05-09 22:50:12]

LGTM with one nit

https://codereview.chromium.org/15077006/diff/5001/Source/core/dom/Document.idl
File Source/core/dom/Document.idl (right):

https://codereview.chromium.org/15077006/diff/5001/Source/core/dom/Document.i...
Source/core/dom/Document.idl:295: [PerWorldBindings] readonly attribute unsigned
long childElementCount;
These probably don't need PerWorldBindings.  They're unlikely to be called in
tight loops.

[commit-bot: I haz the power, 2013-05-10 14:03:59]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/arv@chromium.org/15077006/9001

[commit-bot: I haz the power, 2013-05-10 14:04:04]

Failed to apply patch for Source/core/dom/ContainerNode.cpp:
While running patch -p1 --forward --force --no-backup-if-mismatch;
  patching file Source/core/dom/ContainerNode.cpp
  Hunk #1 FAILED at 30.
  Hunk #2 succeeded at 824 (offset -1 lines).
  1 out of 2 hunks FAILED -- saving rejects to file
Source/core/dom/ContainerNode.cpp.rej

Patch:       Source/core/dom/ContainerNode.cpp
Index: Source/core/dom/ContainerNode.cpp
diff --git a/Source/core/dom/ContainerNode.cpp
b/Source/core/dom/ContainerNode.cpp
index
4256a5986c0edf602b926724a543e38404e899b9..52b0a0244163a50830014a9fda54da8760c0ce27
100644
--- a/Source/core/dom/ContainerNode.cpp
+++ b/Source/core/dom/ContainerNode.cpp
@@ -30,9 +30,11 @@
 #include "core/dom/EventNames.h"
 #include "core/dom/ExceptionCode.h"
 #include "core/dom/MutationEvent.h"
+#include "core/dom/NodeRareData.h"
 #include "core/dom/NodeRenderStyle.h"
 #include "core/dom/NodeTraversal.h"
 #include "core/dom/TemplateContentDocumentFragment.h"
+#include "core/html/HTMLCollection.h"
 #include "core/html/shadow/InsertionPoint.h"
 #include "core/inspector/InspectorInstrumentation.h"
 #include "core/loader/cache/MemoryCache.h"
@@ -825,6 +827,35 @@ void ContainerNode::setHovered(bool over)
     }
 }
 
+PassRefPtr<HTMLCollection> ContainerNode::children()
+{
+    return
ensureRareData()->ensureNodeLists()->addCacheWithAtomicName<HTMLCollection>(this,
NodeChildren);
+}
+
+Element* ContainerNode::firstElementChild() const
+{
+    return ElementTraversal::firstWithin(this);
+}
+
+Element* ContainerNode::lastElementChild() const
+{
+    Node* n = lastChild();
+    while (n && !n->isElementNode())
+        n = n->previousSibling();
+    return toElement(n);
+}
+
+unsigned ContainerNode::childElementCount() const
+{
+    unsigned count = 0;
+    Node* n = firstChild();
+    while (n) {
+        count += n->isElementNode();
+        n = n->nextSibling();
+    }
+    return count;
+}
+
 unsigned ContainerNode::childNodeCount() const
 {
     unsigned count = 0;

[commit-bot: I haz the power, 2013-05-10 14:17:24]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/arv@chromium.org/15077006/19001

[commit-bot: I haz the power, 2013-05-10 21:12:18]

Retried try job too often on win_layout for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=win_layout...

[commit-bot: I haz the power, 2013-05-13 14:14:33]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/arv@chromium.org/15077006/23001

[commit-bot: I haz the power, 2013-05-13 14:49:15]

Retried try job too often on linux_layout_rel for step(s) webkit_tests
http://build.chromium.org/p/tryserver.chromium/buildstatus?builder=linux_layo...

[commit-bot: I haz the power, 2013-05-13 16:17:21]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/arv@chromium.org/15077006/23001

[commit-bot: I haz the power, 2013-05-13 18:30:06]

Change committed as 150240