Move viewport unit resolution to style recalc time

Source/core/css/resolver/ViewportStyleResolver.cpp

Index: Source/core/css/resolver/ViewportStyleResolver.cpp
diff --git a/Source/core/css/resolver/ViewportStyleResolver.cpp b/Source/core/css/resolver/ViewportStyleResolver.cpp
index 61894a2458a283c32027c6837af2366d13c7fd3a..f10f893d59855b3cef374193f98895c14d422e47 100644
--- a/Source/core/css/resolver/ViewportStyleResolver.cpp
+++ b/Source/core/css/resolver/ViewportStyleResolver.cpp
@@ -31,6 +31,7 @@
 #include "core/css/resolver/ViewportStyleResolver.h"
 
 #include "CSSValueKeywords.h"
+#include "core/css/CSSPrimitiveValueMappings.h"
 #include "core/css/CSSToLengthConversionData.h"
 #include "core/css/StylePropertySet.h"
 #include "core/css/StyleRule.h"
@@ -183,25 +184,21 @@ Length ViewportStyleResolver::viewportLengthValue(CSSPropertyID id) const
 
     CSSPrimitiveValue* primitiveValue = toCSSPrimitiveValue(value.get());
 
-    if (primitiveValue->isLength())
-        return primitiveValue->computeLength<Length>(CSSToLengthConversionData(m_document->renderStyle(), m_document->renderStyle(), 1.0f));
+    if (primitiveValue->getValueID() == CSSValueInternalExtendToZoom)
+        return Length(ExtendToZoom);
 
-    if (primitiveValue->isViewportPercentageLength())
-        return primitiveValue->viewportPercentageLength();
+    RenderStyle* documentStyle = m_document->renderStyle();
 
-    if (primitiveValue->isPercentage())
-        return Length(primitiveValue->getFloatValue(), Percent);
+    // If we have viewport units the conversion will mark the document style as having viewport units.
+    bool documentStyleHasViewportUnits = documentStyle->hasViewportUnits();
+    documentStyle->setHasViewportUnits(false);
+    Length result = primitiveValue->convertToLength<AnyConversion>(CSSToLengthConversionData(documentStyle, documentStyle, m_document->renderView(), 1.0f));
+    if (documentStyle->hasViewportUnits())
+        m_document->setHasViewportUnits();
+    documentStyle->setHasViewportUnits(documentStyleHasViewportUnits);
 
-    switch (primitiveValue->getValueID()) {
-    case CSSValueInternalExtendToZoom:
-        return Length(ExtendToZoom);
-    case CSSValueAuto:
-        return Length();
-    default:
-        // Unrecognized keyword.
-        ASSERT_NOT_REACHED();
-        return Length(0, Fixed);
-    }
+    ASSERT(!result.isUndefined());
+    return result;
 }
 
 } // namespace WebCore