Add srcset negative x descriptor value tests

Source/core/html/parser/HTMLSrcsetParserTest.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/html/parser/HTMLSrcsetParser.h"
 
 #include <gtest/gtest.h>
 #include <limits.h>
 
 namespace WebCore {
 
 typedef struct {
     float deviceScaleFactor;
     int effectiveSize;
     const char* srcInput;
     const char* srcsetInput;
     const char* outputURL;
     float outputScaleFactor;
     int outputResourceWidth;
 } TestCase;
 
 TEST(HTMLSrcsetParserTest, Basic)
 {
     TestCase testCases[] = {
         {2.0, -1, "", "1x.gif 1x, 2x.gif 2x", "2x.gif", 2.0, -1},
         {2.0, -1, "", "1x.gif 1x, 2x.gif -2x", "1x.gif", 1.0, -1},
+        {2.0, -1, "", "0x.gif 0x", "0x.gif", 0.0, -1},
+        {2.0, -1, "", "0x.gif -0x", "0x.gif", 0.0, -1},
+        {2.0, -1, "", "neg.gif -2x", "", 1.0, -1},
         {2.0, -1, "", "1x.gif 1x, 2x.gif 2q", "1x.gif", 1.0, -1},
         {2.0, -1, "1x.gif 1x, 2x.gif 2x", "1x.gif 1x, 2x.gif 2x", "2x.gif", 2.0, -1},
         {1.0, -1, "1x.gif 1x, 2x.gif 2x", "1x.gif 1x, 2x.gif 2x", "1x.gif", 1.0, -1},
         {1.0, -1, "1x.gif 1x, 2x.gif 2x", "", "1x.gif 1x, 2x.gif 2x", 1.0, -1},
         {2.0, -1, "src.gif", "1x.gif 1x, 2x.gif 2x", "2x.gif", 2.0, -1},
         {1.0, -1, "src.gif", "1x.gif 1x, 2x.gif 2x", "1x.gif", 1.0, -1},
         {1.0, -1, "src.gif", "2x.gif 2x", "src.gif", 1.0, -1},
         {2.0, -1, "src.gif", "2x.gif 2x", "2x.gif", 2.0, -1},
         {1.5, -1, "src.gif", "2x.gif 2x", "2x.gif", 2.0, -1},
         {2.5, -1, "src.gif", "2x.gif 2x", "2x.gif", 2.0, -1},
@@ skipping 25 matching lines @@
     for (unsigned i = 0; testCases[i].srcInput; ++i) {
         TestCase test = testCases[i];
         ImageCandidate candidate = bestFitSourceForImageAttributes(test.deviceScaleFactor, test.effectiveSize, test.srcInput, test.srcsetInput);
         ASSERT_EQ(test.outputScaleFactor, candidate.scaleFactor());
         ASSERT_EQ(test.outputResourceWidth, candidate.resourceWidth());
         ASSERT_STREQ(test.outputURL, candidate.toString().ascii().data());
     }
 }
 
 } // namespace