Move web-platform-tests to wpt (part 1 of 2)

third_party/WebKit/LayoutTests/imported/wpt/html/syntax/parsing/common.js

 function mark_diffs(expected, actual) {
   var expected_lines = expected.split("\n");
   var actual_lines = actual.split("\n");
 
   var max_length = Math.max(expected_lines.length, actual_lines.length);
 
   var expected_diff = ["code", {}];
   var actual_diff = ["code", {}];
 
   for (var i=0; i<max_length; i++) {
     if (expected_lines[i] === actual_lines[i]) {
       expected_diff.push(expected_lines[i] + "\n");
       actual_diff.push(actual_lines[i] + "\n");
     } else {
       if (expected_lines[i]) {
         expected_diff.push(["span", {style:"color:red"}, expected_lines[i] + "\n"]);
       }
       if (actual_lines[i]) {
         actual_diff.push(["span", {style:"color:red"}, actual_lines[i] + "\n"]);
       }
     }
   }
   return [expected_diff, actual_diff];
 }