Remove unprefixing logic from interpolation test helper

LayoutTests/animations/interpolation/resources/interpolation-test.js

 /*
  * Copyright (C) 2013 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * 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
@@ skipping 179 matching lines @@
 
   function describeCSSTest(params) {
     return 'CSS ' + params.property + ': from [' + params.from + '] to [' + params.to + ']';
   }
 
   function describeWATest(params) {
     return 'element.animate() ' + convertPropertyToCamelCase(params.property) + ': from [' + params.from + '] to [' + params.to + ']';
   }
 
   function assertInterpolation(params, expectations) {
-    // If the prefixed property is not supported, try to unprefix it.
-    if (/^-[^-]+-/.test(params.property) && !CSS.supports(params.property, 'initial')) {
-      var unprefixed = params.property.replace(/^-[^-]+-/, '');
-      if (CSS.supports(unprefixed, 'initial')) {
-        params.property = unprefixed;
-      }
-    }
     var testId = defineKeyframes(params);
     var nextCaseId = 0;
     var cssTestContainer = createTestContainer(describeCSSTest(params), testId);
     cssTests.appendChild(cssTestContainer);
     if (webAnimationsTest) {
       var waTestContainer = createTestContainer(describeWATest(params), testId);
       waTests.appendChild(waTestContainer);
     }
     expectations.forEach(function(expectation) {
       cssTestContainer.appendChild(makeInterpolationTest(
@@ skipping 203 matching lines @@
       finishTest();
     }, 10000);
   }
 
   window.runAsRefTest = runAsRefTest;
   window.testInterpolationAt = testInterpolationAt;
   window.assertInterpolation = assertInterpolation;
   window.convertToReference = convertToReference;
   window.afterTest = afterTest;
 })();