Count internal use of DOMImplementation::hasFeature() returning false

This is the only internal usage of DOMImplementation::hasFeature(), and
the only way that svg:requiredFeatures is observable, other than the
it->isEmpty() case.

If usage is low, DOMImplementation.hasFeature() and this internal usage
can be changed together, see
https://groups.google.com/a/chromium.org/d/msg/blink-dev/r2aARnIHG4k/_dN33g65mYgJ

Review URL: https://codereview.chromium.org/712813002

git-svn-id: svn://svn.chromium.org/blink/trunk@185133 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -558,6 +558,7 @@ public:
         InputTypeSubmit = 591,
         InputTypeSubmitWithValue = 592,
         SetReferrerPolicy = 593,
+        DOMImplementationHasFeatureReturnFalseInternal = 594,
 
         // Add new features immediately above this line. Don't change assigned
         // numbers of any item, and don't reuse removed slots.

third_party/WebKit/Source/core/svg/SVGAnimationElement.h

@@ -167,7 +167,7 @@ protected:
     void setCalcMode(CalcMode calcMode) { m_calcMode = calcMode; }
 
 private:
-    virtual bool isValid() const override final { return SVGTests::isValid(); }
+    virtual bool isValid() const override final { return SVGTests::isValid(document()); }
 
     virtual void animationAttributeChanged() override;
     void setAttributeType(const AtomicString&);

third_party/WebKit/Source/core/svg/SVGCursorElement.h

@@ -52,7 +52,7 @@ public:
 private:
     explicit SVGCursorElement(Document&);
 
-    virtual bool isValid() const override { return SVGTests::isValid(); }
+    virtual bool isValid() const override { return SVGTests::isValid(document()); }
 
     bool isSupportedAttribute(const QualifiedName&);
     virtual void parseAttribute(const QualifiedName&, const AtomicString&) override;

third_party/WebKit/Source/core/svg/SVGGraphicsElement.h

@@ -62,7 +62,7 @@ public:
     virtual void toClipPath(Path&);
     virtual RenderObject* createRenderer(RenderStyle*) override;
 
-    virtual bool isValid() const override final { return SVGTests::isValid(); }
+    virtual bool isValid() const override final { return SVGTests::isValid(document()); }
 
     SVGAnimatedTransformList* transform() { return m_transform.get(); }
     const SVGAnimatedTransformList* transform() const { return m_transform.get(); }

third_party/WebKit/Source/core/svg/SVGMaskElement.h

@@ -46,7 +46,7 @@ public:
 private:
     explicit SVGMaskElement(Document&);
 
-    virtual bool isValid() const override { return SVGTests::isValid(); }
+    virtual bool isValid() const override { return SVGTests::isValid(document()); }
     virtual bool needsPendingResourceHandling() const override { return false; }
 
     bool isSupportedAttribute(const QualifiedName&);

third_party/WebKit/Source/core/svg/SVGPatternElement.h

@@ -62,7 +62,7 @@ public:
 private:
     explicit SVGPatternElement(Document&);
 
-    virtual bool isValid() const override { return SVGTests::isValid(); }
+    virtual bool isValid() const override { return SVGTests::isValid(document()); }
     virtual bool needsPendingResourceHandling() const override { return false; }
 
     bool isSupportedAttribute(const QualifiedName&);

third_party/WebKit/Source/core/svg/SVGTests.cpp

@@ -24,8 +24,9 @@
 
 #include "core/SVGNames.h"
 #include "core/dom/DOMImplementation.h"
-#include "platform/Language.h"
+#include "core/frame/UseCounter.h"
 #include "core/svg/SVGElement.h"
+#include "platform/Language.h"
 
 namespace blink {
 
@@ -47,15 +48,19 @@ bool SVGTests::hasExtension(const String&)
     return false;
 }
 
-bool SVGTests::isValid() const
+bool SVGTests::isValid(Document& document) const
 {
     if (m_requiredFeatures->isSpecified()) {
         const Vector<String>& requiredFeatures = m_requiredFeatures->value()->values();
         Vector<String>::const_iterator it = requiredFeatures.begin();
         Vector<String>::const_iterator itEnd = requiredFeatures.end();
         for (; it != itEnd; ++it) {
-            if (it->isEmpty() || !DOMImplementation::hasFeature(*it, String()))
+            if (it->isEmpty())
                 return false;
+            if (!DOMImplementation::hasFeature(*it, String())) {
+                UseCounter::count(document, UseCounter::DOMImplementationHasFeatureReturnFalseInternal);
+                return false;
+            }
         }
     }
 

third_party/WebKit/Source/core/svg/SVGTests.h

@@ -26,6 +26,7 @@
 
 namespace blink {
 
+class Document;
 class QualifiedName;
 class SVGElement;
 
@@ -37,7 +38,7 @@ public:
     SVGStringListTearOff* systemLanguage() { return m_systemLanguage->tearOff(); }
     bool hasExtension(const String&);
 
-    bool isValid() const;
+    bool isValid(Document&) const;
 
     bool parseAttribute(const QualifiedName&, const AtomicString&);
     bool isKnownAttribute(const QualifiedName&);