Change handling of sub-pixel borders to round

third_party/WebKit/Source/core/css/resolver/StyleBuilderConverter.h

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
  * copyright notice, this list of conditions and the following disclaimer
  * in the documentation and/or other materials provided with the
  * distribution.
  *     * Neither the name of Google Inc. nor the names of its
@@ skipping 221 matching lines @@
   // FIXME: We are moving to use the full page zoom implementation to handle
   // high-dpi.  In that case specyfing a border-width of less than 1px would
   // result in a border that is one device pixel thick.  With this change that
   // would instead be rounded up to 2 device pixels.  Consider clamping it to
   // device pixels or zoom adjusted CSS pixels instead of raw CSS pixels.
   // Reference crbug.com/485650 and crbug.com/382483
   double result =
       primitiveValue.computeLength<double>(state.cssToLengthConversionData());
   if (result > 0.0 && result < 1.0)
     return 1.0;
-  return clampTo<T>(roundForImpreciseConversion<T>(result),
+  return clampTo<T>(roundForImpreciseConversion<T>(round(result)),
                     defaultMinimumForClamp<T>(), defaultMaximumForClamp<T>());
 }
 
 template <CSSValueID cssValueFor0, CSSValueID cssValueFor100>
 Length StyleBuilderConverter::convertPositionLength(StyleResolverState& state,
                                                     const CSSValue& value) {
   if (value.isValuePair()) {
     const CSSValuePair& pair = toCSSValuePair(value);
     Length length = StyleBuilderConverter::convertLength(state, pair.second());
     if (toCSSIdentifierValue(pair.first()).getValueID() == cssValueFor0)
@@ skipping 24 matching lines @@
                                                   const CSSValue& value) {
   if (value.isStringValue())
     return AtomicString(toCSSStringValue(value).value());
   DCHECK_EQ(toCSSIdentifierValue(value).getValueID(), IdForNone);
   return nullAtom;
 }
 
 }  // namespace blink
 
 #endif