Add support for CSSValue->CSSSimpleLength when it is a percentage.

third_party/WebKit/Source/core/css/cssom/CSSSimpleLength.cpp

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "core/css/cssom/CSSSimpleLength.h"
 
 #include "bindings/core/v8/ExceptionState.h"
 #include "core/css/CSSPrimitiveValue.h"
 #include "core/css/cssom/CSSCalcLength.h"
 #include "wtf/text/StringBuilder.h"
 
 namespace blink {
 
 CSSSimpleLength* CSSSimpleLength::create(double value, const String& type, ExceptionState& exceptionState)
 {
     CSSPrimitiveValue::UnitType unit = CSSLengthValue::unitFromName(type);
     if (!CSSLengthValue::isSupportedLengthUnit(unit)) {
         exceptionState.throwTypeError("Invalid unit for CSSSimpleLength: " + type);
         return nullptr;
     }
     return new CSSSimpleLength(value, unit);
 }
 
 CSSSimpleLength* CSSSimpleLength::fromCSSValue(const CSSPrimitiveValue& value)
 {
-    DCHECK(value.isLength());
+    DCHECK(value.isLength() || value.isPercentage());
+    if (value.isPercentage())
+        return new CSSSimpleLength(value.getDoubleValue(), CSSPrimitiveValue::UnitType::Percentage);
     return new CSSSimpleLength(value.getDoubleValue(), value.typeWithCalcResolved());
 }
 
 bool CSSSimpleLength::containsPercent() const
 {
     return lengthUnit() == CSSPrimitiveValue::UnitType::Percentage;
 }
 
+String CSSSimpleLength::unit() const
+{
+    if (lengthUnit() == CSSPrimitiveValue::UnitType::Percentage)
+        return "percent";
+    return CSSPrimitiveValue::unitTypeToString(m_unit);
+}
+
 CSSLengthValue* CSSSimpleLength::addInternal(const CSSLengthValue* other)
 {
     const CSSSimpleLength* o = toCSSSimpleLength(other);
     DCHECK_EQ(m_unit, o->m_unit);
     return create(m_value + o->value(), m_unit);
 }
 
 CSSLengthValue* CSSSimpleLength::subtractInternal(const CSSLengthValue* other)
 {
     const CSSSimpleLength* o = toCSSSimpleLength(other);
@@ skipping 11 matching lines @@
     DCHECK_NE(x, 0);
     return create(m_value / x, m_unit);
 }
 
 CSSValue* CSSSimpleLength::toCSSValue() const
 {
     return CSSPrimitiveValue::create(m_value, m_unit);
 }
 
 } // namespace blink