Support 'extend-to-zoom' viewport descriptor value

Source/core/css/CSSParser-in.cpp

Index: Source/core/css/CSSParser-in.cpp
diff --git a/Source/core/css/CSSParser-in.cpp b/Source/core/css/CSSParser-in.cpp
index 6d488057a4e092d7ed4c1d009bb61710bd34276d..945a438f01e9dd2709afc99e65b7fb349c4fbd6f 100644
--- a/Source/core/css/CSSParser-in.cpp
+++ b/Source/core/css/CSSParser-in.cpp
@@ -11406,9 +11406,6 @@ unsigned CSSParser::safeUserStringTokenOffset()
 
 StyleRuleBase* CSSParser::createViewportRule()
 {
-    if (!RuntimeEnabledFeatures::cssViewportEnabled())
-        return 0;
-
     m_allowImportRules = m_allowNamespaceDeclarations = false;
 
     RefPtr<StyleRuleViewport> rule = StyleRuleViewport::create();
@@ -11425,8 +11422,6 @@ StyleRuleBase* CSSParser::createViewportRule()
 
 bool CSSParser::parseViewportProperty(CSSPropertyID propId, bool important)
 {
-    ASSERT(RuntimeEnabledFeatures::cssViewportEnabled());
-
     CSSParserValue* value = m_valueList->current();
     if (!value)
         return false;
@@ -11435,11 +11430,11 @@ bool CSSParser::parseViewportProperty(CSSPropertyID propId, bool important)
     bool validPrimitive = false;
 
     switch (propId) {
-    case CSSPropertyMinWidth: // auto | <length> | <percentage>
+    case CSSPropertyMinWidth: // auto | extend-to-zoom | <length> | <percentage>
     case CSSPropertyMaxWidth:
     case CSSPropertyMinHeight:
     case CSSPropertyMaxHeight:
-        if (id == CSSValueAuto)
+        if (id == CSSValueAuto || id == CSSValueInternalExtendToZoom)
             validPrimitive = true;
         else
             validPrimitive = (!id && validUnit(value, FLength | FPercent | FNonNeg));
@@ -11485,7 +11480,6 @@ bool CSSParser::parseViewportProperty(CSSPropertyID propId, bool important)
 
 bool CSSParser::parseViewportShorthand(CSSPropertyID propId, CSSPropertyID first, CSSPropertyID second, bool important)
 {
-    ASSERT(RuntimeEnabledFeatures::cssViewportEnabled());
     unsigned numValues = m_valueList->size();
 
     if (numValues > 2)