Use new Traversal<> API more in the code base

Use new Traversal<> API more in the code base to simplify code a bit and
increase readability.

R=esprehn@chromium.org, adamk@chromium.org

Review URL: https://codereview.chromium.org/420193007

git-svn-id: svn://svn.chromium.org/blink/trunk@179067 bbb929c8-8fbe-4397-9dbb-9b2b20218538

third_party/WebKit/Source/core/css/AffectedByFocusTest.cpp

@@ -59,16 +59,16 @@ void AffectedByFocusTest::setHtmlInnerHTML(const char* htmlContent)
 void AffectedByFocusTest::checkElements(ElementResult expected[], unsigned expectedCount) const
 {
     unsigned i = 0;
-    Element* elm = document().body();
+    HTMLElement* element = document().body();
 
-    for (; elm && i < expectedCount; elm = ElementTraversal::next(*elm), ++i) {
-        ASSERT_TRUE(elm->hasTagName(expected[i].tag));
-        ASSERT(elm->renderStyle());
-        ASSERT_EQ(expected[i].affectedBy, elm->renderStyle()->affectedByFocus());
-        ASSERT_EQ(expected[i].childrenOrSiblingsAffectedBy, elm->childrenOrSiblingsAffectedByFocus());
+    for (; element && i < expectedCount; element = Traversal<HTMLElement>::next(*element), ++i) {
+        ASSERT_TRUE(element->hasTagName(expected[i].tag));
+        ASSERT(element->renderStyle());
+        ASSERT_EQ(expected[i].affectedBy, element->renderStyle()->affectedByFocus());
+        ASSERT_EQ(expected[i].childrenOrSiblingsAffectedBy, element->childrenOrSiblingsAffectedByFocus());
     }
 
-    ASSERT(!elm && i == expectedCount);
+    ASSERT(!element && i == expectedCount);
 }
 
 // A global :focus rule in html.css currently causes every single element to be

third_party/WebKit/Source/core/dom/shadow/ShadowRoot.cpp

@@ -316,10 +316,8 @@ const WillBeHeapVector<RefPtrWillBeMember<InsertionPoint> >& ShadowRoot::descend
         return emptyList;
 
     WillBeHeapVector<RefPtrWillBeMember<InsertionPoint> > insertionPoints;
-    for (Element* element = ElementTraversal::firstWithin(*this); element; element = ElementTraversal::next(*element, this)) {
-        if (element->isInsertionPoint())
-            insertionPoints.append(toInsertionPoint(element));
-    }
+    for (InsertionPoint* insertionPoint = Traversal<InsertionPoint>::firstWithin(*this); insertionPoint; insertionPoint = Traversal<InsertionPoint>::next(*insertionPoint, this))
+        insertionPoints.append(insertionPoint);
 
     ensureShadowRootRareData()->setDescendantInsertionPoints(insertionPoints);
 

third_party/WebKit/Source/core/html/HTMLFieldSetElement.cpp

@@ -60,10 +60,8 @@ void HTMLFieldSetElement::trace(Visitor* visitor)
 
 void HTMLFieldSetElement::invalidateDisabledStateUnder(Element& base)
 {
-    for (Element* element = ElementTraversal::firstWithin(base); element; element = ElementTraversal::next(*element, &base)) {
-        if (element->isFormControlElement())
-            toHTMLFormControlElement(element)->ancestorDisabledStateWasChanged();
-    }
+    for (HTMLFormControlElement* element = Traversal<HTMLFormControlElement>::firstWithin(base); element; element = Traversal<HTMLFormControlElement>::next(*element, &base))
+        element->ancestorDisabledStateWasChanged();
 }
 
 void HTMLFieldSetElement::disabledAttributeChanged()

third_party/WebKit/Source/core/html/HTMLLabelElement.cpp

@@ -37,15 +37,6 @@ namespace blink {
 
 using namespace HTMLNames;
 
-static bool supportsLabels(const Element& element)
-{
-    if (!element.isHTMLElement())
-        return false;
-    if (!toHTMLElement(element).isLabelable())
-        return false;
-    return toLabelableElement(element).supportLabels();
-}
-
 inline HTMLLabelElement::HTMLLabelElement(Document& document)
     : HTMLElement(labelTag, document)
 {
@@ -67,16 +58,15 @@ LabelableElement* HTMLLabelElement::control() const
         // Search the children and descendants of the label element for a form element.
         // per http://dev.w3.org/html5/spec/Overview.html#the-label-element
         // the form element must be "labelable form-associated element".
-        for (Element* element = ElementTraversal::next(*this, this); element; element = ElementTraversal::next(*element, this)) {
-            if (!supportsLabels(*element))
-                continue;
-            return toLabelableElement(element);
+        for (LabelableElement* element = Traversal<LabelableElement>::next(*this, this); element; element = Traversal<LabelableElement>::next(*element, this)) {
+            if (element->supportLabels())
+                return element;
         }
         return 0;
     }
 
     if (Element* element = treeScope().getElementById(controlId)) {
-        if (supportsLabels(*element))
+        if (isLabelableElement(*element) && toLabelableElement(*element).supportLabels())
             return toLabelableElement(element);
     }
 

third_party/WebKit/Source/core/html/track/vtt/VTTRegion.cpp

@@ -374,8 +374,9 @@ void VTTRegion::displayLastVTTCueBox()
 
     // Find first cue that is not entirely displayed and scroll it upwards.
     for (Element* child = ElementTraversal::firstChild(*m_cueContainer); child && !m_scrollTimer.isActive(); child = ElementTraversal::nextSibling(*child)) {
-        float childTop = toHTMLDivElement(child)->getBoundingClientRect()->top();
-        float childBottom = toHTMLDivElement(child)->getBoundingClientRect()->bottom();
+        RefPtrWillBeRawPtr<ClientRect> clientRect = child->getBoundingClientRect();
+        float childTop = clientRect->top();
+        float childBottom = clientRect->bottom();
 
         if (regionBottom >= childBottom)
             continue;

third_party/WebKit/Source/core/rendering/svg/RenderSVGResourceClipper.cpp

@@ -91,14 +91,14 @@ bool RenderSVGResourceClipper::tryPathOnlyClipping(GraphicsContext* context,
     WindRule clipRule = RULE_NONZERO;
     Path clipPath = Path();
 
-    for (Element* childElement = ElementTraversal::firstChild(*element()); childElement; childElement = ElementTraversal::nextSibling(*childElement)) {
+    for (SVGElement* childElement = Traversal<SVGElement>::firstChild(*element()); childElement; childElement = Traversal<SVGElement>::nextSibling(*childElement)) {
         RenderObject* renderer = childElement->renderer();
         if (!renderer)
             continue;
         // Only shapes or paths are supported for direct clipping. We need to fallback to masking for texts.
         if (renderer->isSVGText())
             return false;
-        if (!childElement->isSVGElement() || !toSVGElement(childElement)->isSVGGraphicsElement())
+        if (!childElement->isSVGGraphicsElement())
             continue;
         SVGGraphicsElement* styled = toSVGGraphicsElement(childElement);
         RenderStyle* style = renderer->style();

third_party/WebKit/Source/core/rendering/svg/RenderSVGResourceMasker.cpp

@@ -137,9 +137,9 @@ PassRefPtr<DisplayList> RenderSVGResourceMasker::asDisplayList(GraphicsContext*
     // with local clips/mask, which may yield incorrect results when mixing objectBoundingBox and
     // userSpaceOnUse units (http://crbug.com/294900).
     context->beginRecording(strokeBoundingBox());
-    for (Element* childElement = ElementTraversal::firstChild(*element()); childElement; childElement = ElementTraversal::nextSibling(*childElement)) {
+    for (SVGElement* childElement = Traversal<SVGElement>::firstChild(*element()); childElement; childElement = Traversal<SVGElement>::nextSibling(*childElement)) {
         RenderObject* renderer = childElement->renderer();
-        if (!childElement->isSVGElement() || !renderer)
+        if (!renderer)
             continue;
         RenderStyle* style = renderer->style();
         if (!style || style->display() == NONE || style->visibility() != VISIBLE)

third_party/WebKit/Source/core/rendering/svg/RenderSVGResourcePattern.cpp

@@ -258,8 +258,8 @@ PassOwnPtr<ImageBuffer> RenderSVGResourcePattern::createTileImage(const PatternA
         contentTransformation = tileImageTransform;
 
     // Draw the content into the ImageBuffer.
-    for (Element* element = ElementTraversal::firstChild(*attributes.patternContentElement()); element; element = ElementTraversal::nextSibling(*element)) {
-        if (!element->isSVGElement() || !element->renderer())
+    for (SVGElement* element = Traversal<SVGElement>::firstChild(*attributes.patternContentElement()); element; element = Traversal<SVGElement>::nextSibling(*element)) {
+        if (!element->renderer())
             continue;
         if (element->renderer()->needsLayout())
             return nullptr;