Add a usecounter for SMIL elements in the document

The current SVGAnimation usecounter [1] is skewed by Modernizr [2] and
doesn't count the other animation types such as <animateMotion>. This
patch adds a new usecounter for SMIL animation elements that are in
the document. I manually confirmed this does not fire on the
Modernizr test page [3] whereas the old SVGAnimation counter does.

[1] http://www.chromestatus.com/metrics/feature/timeline/popularity/90
[2] https://github.com/Modernizr/Modernizr/blob/v2.8.3/modernizr.js#L832-L835
[3] http://modernizr.github.io/Modernizr/test/

BUG=258298

Review URL: https://codereview.chromium.org/424273003

git-svn-id: svn://svn.chromium.org/blink/trunk@179191 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/frame/UseCounter.h

@@ -490,6 +490,7 @@ public:
         HTMLObjectElementStandby = 498,
         HTMLTableCellElementChar = 499,
         HTMLTableCellElementCharOff = 500,
+        SVGSMILElementInDocument = 501,
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.
         // Also, run update_use_counter_feature_enum.py in chromium/src/tools/metrics/histograms/

third_party/WebKit/Source/core/svg/animation/SVGSMILElement.cpp

@@ -33,6 +33,7 @@
 #include "core/events/Event.h"
 #include "core/events/EventListener.h"
 #include "core/events/EventSender.h"
+#include "core/frame/UseCounter.h"
 #include "core/svg/SVGDocumentExtensions.h"
 #include "core/svg/SVGSVGElement.h"
 #include "core/svg/SVGURIReference.h"
@@ -313,6 +314,8 @@ Node::InsertionNotificationRequest SVGSMILElement::insertedInto(ContainerNode* r
     if (!rootParent->inDocument())
         return InsertionDone;
 
+    UseCounter::count(document(), UseCounter::SVGSMILElementInDocument);
+
     setAttributeName(constructQualifiedName(this, fastGetAttribute(SVGNames::attributeNameAttr)));
     SVGSVGElement* owner = ownerSVGElement();
     if (!owner)