Add forEach() to CSSVariablesMap

Source/core/css/CSSComputedStyleDeclaration.cpp

Index: Source/core/css/CSSComputedStyleDeclaration.cpp
diff --git a/Source/core/css/CSSComputedStyleDeclaration.cpp b/Source/core/css/CSSComputedStyleDeclaration.cpp
index dd2e82d38908db2c89904c793b053b3e464b3a1c..89193818f9b2312dfedbdcfb3d2b3e695850f465 100644
--- a/Source/core/css/CSSComputedStyleDeclaration.cpp
+++ b/Source/core/css/CSSComputedStyleDeclaration.cpp
@@ -3186,6 +3186,35 @@ void CSSComputedStyleDeclaration::clearVariables(ExceptionState& es)
     es.throwDOMException(NoModificationAllowedError, "Failed to clear variables from a computed 'CSSStyleDeclaration': computed styles are read-only.");
 }
 
+CSSComputedStyleDeclaration::ComputedCSSVariablesIterator::ComputedCSSVariablesIterator(const HashMap<AtomicString, String>* variables)
+    : m_active(variables)
+{
+    ASSERT(RuntimeEnabledFeatures::cssVariablesEnabled());
+    if (m_active) {
+        m_it = variables->begin();
+        m_end = variables->end();
+    }
+}
+
+void CSSComputedStyleDeclaration::ComputedCSSVariablesIterator::advance()
+{
+    ASSERT(m_active);
+    ++m_it;
+    m_active = !atEnd();
+}
+
+AtomicString CSSComputedStyleDeclaration::ComputedCSSVariablesIterator::name() const
+{
+    ASSERT(m_active);
+    return m_it->key;
+}
+
+String CSSComputedStyleDeclaration::ComputedCSSVariablesIterator::value() const
+{
+    ASSERT(m_active);
+    return m_it->value;
+}
+
 PassRefPtr<CSSValueList> CSSComputedStyleDeclaration::valuesForBackgroundShorthand() const
 {
     static const CSSPropertyID propertiesBeforeSlashSeperator[5] = { CSSPropertyBackgroundColor, CSSPropertyBackgroundImage,