Enable float source size

Source/core/css/parser/SizesCalcParser.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/parser/SizesCalcParser.h"
 
 #include "core/css/MediaValues.h"
 #include "core/css/parser/MediaQueryToken.h"
 
 namespace blink {
 
 SizesCalcParser::SizesCalcParser(MediaQueryTokenIterator start, MediaQueryTokenIterator end, PassRefPtr<MediaValues> mediaValues)
     : m_mediaValues(mediaValues)
     , m_viewportDependant(false)
     , m_result(0)
 {
     m_isValid = calcToReversePolishNotation(start, end) && calculate();
 }
 
-unsigned SizesCalcParser::result() const
+float SizesCalcParser::result() const
 {
     ASSERT(m_isValid);
     return m_result;
 }
 
 static bool operatorPriority(UChar cc, bool& highPriority)
 {
     if (cc == '+' || cc == '-')
         highPriority = false;
     else if (cc == '*' || cc == '/')
@@ skipping 173 matching lines @@
     Vector<SizesCalcValue> stack;
     for (Vector<SizesCalcValue>::iterator it = m_valueList.begin(); it != m_valueList.end(); ++it) {
         if (it->operation == 0) {
             stack.append(*it);
         } else {
             if (!operateOnStack(stack, it->operation))
                 return false;
         }
     }
     if (stack.size() == 1 && stack.last().isLength) {
-        m_result = clampTo<unsigned>(stack.last().value);
+        m_result = std::max(clampTo<float>(stack.last().value), (float)0.0);
         return true;
     }
     return false;
 }
 
 } // namespace blink