CSS4: Implement :placeholder-shown pseudo class

Source/core/html/HTMLInputElement.cpp

Index: Source/core/html/HTMLInputElement.cpp
diff --git a/Source/core/html/HTMLInputElement.cpp b/Source/core/html/HTMLInputElement.cpp
index f14561f81f06a0416f789f4e2a8c18d358011798..4cbb77c6d991682f83159740eeb4c1d6d28b1ee7 100644
--- a/Source/core/html/HTMLInputElement.cpp
+++ b/Source/core/html/HTMLInputElement.cpp
@@ -119,6 +119,7 @@ HTMLInputElement::HTMLInputElement(Document& document, HTMLFormElement* form, bo
     , m_hasTouchEventHandler(false)
     , m_shouldRevealPassword(false)
     , m_needsToUpdateViewValue(true)
+    , m_isPlaceholderVisible(false)
     // |m_inputType| is lazily created when constructed by the parser to avoid
     // constructing unnecessarily a text inputType and its shadow subtree, just
     // to destroy them when the |type| attribute gets set by the parser to
@@ -700,7 +701,7 @@ void HTMLInputElement::parseAttribute(const QualifiedName& name, const AtomicStr
     } else if (name == valueAttr) {
         // We only need to setChanged if the form is looking at the default value right now.
         if (!hasDirtyValue()) {
-            updatePlaceholderVisibility(false);
+            updatePlaceholderVisibility();
             setNeedsStyleRecalc(SubtreeStyleChange, StyleChangeReasonForTracing::fromAttribute(valueAttr));
         }
         m_needsToUpdateViewValue = true;
@@ -1665,6 +1666,11 @@ bool HTMLInputElement::shouldAppearChecked() const
     return checked() && m_inputType->isCheckable();
 }
 
+void HTMLInputElement::setPlaceholderVisibility(bool visible)
+{
+    m_isPlaceholderVisible = visible;
+}
+
 bool HTMLInputElement::supportsPlaceholder() const
 {
     return m_inputType->supportsPlaceholder();