A thread safe CSS calc parser for sizes

Source/core/css/MediaValues.cpp

 // Copyright 2014 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 "config.h"
 #include "core/css/MediaValues.h"
 
 #include "core/css/CSSHelper.h"
 #include "core/css/MediaValuesCached.h"
 #include "core/css/MediaValuesDynamic.h"
@@ skipping 120 matching lines @@
     // FIXME: We should also try to determine if we know we have a mouse.
     // When we do this, we'll also need to differentiate between known not to
     // have mouse or touch screen (NoPointer) and unknown (UnknownPointer).
     // We could also take into account other preferences like accessibility
     // settings to decide which of the available pointers should be considered
     // "primary".
 
     return MediaValues::UnknownPointer;
 }
 
-bool MediaValues::computeLength(double value, CSSPrimitiveValue::UnitTypes type, unsigned defaultFontSize, unsigned viewportWidth, unsigned viewportHeight, int& result)
+bool MediaValues::computeLengthImpl(double value, CSSPrimitiveValue::UnitTypes type, unsigned defaultFontSize, unsigned viewportWidth, unsigned viewportHeight, double& result)
 {
     // The logic in this function is duplicated from CSSPrimitiveValue::computeLengthDouble
     // because MediaValues::computeLength needs nearly identical logic, but we haven't found a way to make
     // CSSPrimitiveValue::computeLengthDouble more generic (to solve both cases) without hurting performance.
 
     // FIXME - Unite the logic here with CSSPrimitiveValue in a performant way.
     double factor = 0;
     switch (type) {
     case CSSPrimitiveValue::CSS_EMS:
     case CSSPrimitiveValue::CSS_REMS:
@@ skipping 37 matching lines @@
     case CSSPrimitiveValue::CSS_PT:
         factor = cssPixelsPerPoint;
         break;
     case CSSPrimitiveValue::CSS_PC:
         factor = cssPixelsPerPica;
         break;
     default:
         return false;
     }
 
+    result = value * factor;
+    return true;
+
     ASSERT(factor > 0);
-    result = roundForImpreciseConversion<int>(value*factor);
-    return true;
 }
 
 } // namespace