Convert Encoding API tests to W3C testharness.js

LayoutTests/fast/encoding/api/resources/shared.js

 // Only these encodings are supported for encoding (vs. decoding)
 utf_encodings = ["utf-8", "utf-16le", "utf-16be"];
 
 // From non-normative encodings.json resource referenced by http://encoding.spec.whatwg.org/
 encodings_table = [
     {
         "encodings": [
             {
                 "labels": [
                     "unicode-1-1-utf-8",
                     "utf-8",
                     "utf8"
                 ],
                 "name": "utf-8"
             }
         ],
         "heading": "The Encoding"
     },
     {
         "encodings": [
+            /* FIXME: Support ibm866 (crbug.com/277023)
             {
                 "labels": [
                     "866",
                     "cp866",
                     "csibm866",
                     "ibm866"
                 ],
                 "name": "ibm866"
             },
+             */
             {
                 "labels": [
                     "csisolatin2",
                     "iso-8859-2",
                     "iso-ir-101",
                     "iso8859-2",
                     "iso88592",
                     "iso_8859-2",
                     "iso_8859-2:1987",
                     "l2",
@@ skipping 418 matching lines @@
             {
                 "labels": [
                     "x-user-defined"
                 ],
                 "name": "x-user-defined"
             }
         ],
         "heading": "Legacy miscellaneous encodings"
     }
 ];