Move the FileAPI directory from web-platform-tests/ to wpt/.

third_party/WebKit/LayoutTests/imported/wpt/FileAPI/idlharness.worker.js

 importScripts("/resources/testharness.js");
 importScripts("/resources/WebIDLParser.js", "/resources/idlharness.js");
 
 var request = new XMLHttpRequest();
 request.open("GET", "idlharness.idl");
 request.send();
 request.onload = function() {
     var idl_array = new IdlArray();
     var idls = request.responseText;
 
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     idl_array.add_objects({
         Blob: ['new Blob(["TEST"])'],
         File: ['new File(["myFileBits"], "myFileName")'],
         FileReader: ['new FileReader()'],
         FileReaderSync: ['new FileReaderSync()']
     });
 
     idl_array.test();
     done();
 };