Add additive animation support for CSS property translate

third_party/WebKit/Source/core/animation/CSSLengthInterpolationType.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/animation/CSSLengthInterpolationType.h"
 
 #include "core/animation/LengthPropertyFunctions.h"
 #include "core/animation/css/CSSAnimatableValueFactory.h"
 #include "core/css/CSSCalculationValue.h"
 #include "core/css/resolver/StyleBuilder.h"
@@ skipping 228 matching lines @@
 }
 
 // TODO(alancutter): Move this to Length.h.
 static double clampToRange(double x, ValueRange range)
 {
     return (range == ValueRangeNonNegative && x < 0) ? 0 : x;
 }
 
 static Length createLength(double pixels, double percentage, bool hasPercentage, ValueRange range)
 {
-    ASSERT(hasPercentage || percentage == 0);
-    if (pixels && hasPercentage)
+    if (percentage != 0)
+        hasPercentage = true;
+    if (pixels != 0 && hasPercentage)
         return Length(CalculationValue::create(PixelsAndPercent(pixels, percentage), range));
     if (hasPercentage)
         return Length(clampToRange(percentage, range), Percent);
     return Length(CSSPrimitiveValue::clampToCSSLengthRange(clampToRange(pixels, range)), Fixed);
 }
 
 static Length resolveInterpolablePixelsOrPercentageLength(const InterpolableList& values, bool hasPercentage, ValueRange range, double zoom)
 {
     ASSERT(isPixelsOrPercentOnly(values));
     double pixels = toInterpolableNumber(values.get(CSSPrimitiveValue::UnitTypePixels))->value() * zoom;
@@ skipping 77 matching lines @@
             RefPtr<AnimatableValue> after = CSSAnimatableValueFactory::create(cssProperty(), *state.style());
             ASSERT(before->equals(*after));
 #endif
             return;
         }
     }
     StyleBuilder::applyProperty(cssProperty(), state, createCSSValue(values, hasPercentage, m_valueRange).get());
 }
 
 } // namespace blink