Remove unprefixing logic from interpolation test helper

This was helpful to allow a number of tests to run under other browsers, but
as we're starting to unprefix some properties we will add additional tests
instead.

Review URL: https://codereview.chromium.org/212073002

git-svn-id: svn://svn.chromium.org/blink/trunk@170028 bbb929c8-8fbe-4397-9dbb-9b2b20218538

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

@@ -197,13 +197,6 @@
   }
 
   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);