Implement Encoding API

Source/modules/modules.gypi

 {
   'variables': {
     # Experimental hooks for embedder to provide extra IDL and source files.
     #
     # Note: this is not a supported API. If you rely on this, you will be broken
     # from time to time as the code generator changes in backward incompatible
     # ways.
     'extra_blink_module_idl_files': [],
     'extra_blink_module_files': [],
 
     'deprecated_perl_modules_idl_files': [
       '<@(extra_blink_module_idl_files)',
       'crypto/AesCbcParams.idl',
       'crypto/AesKeyGenParams.idl',
       'crypto/Algorithm.idl',
       'crypto/Crypto.idl',
       'crypto/CryptoOperation.idl',
       'crypto/HmacParams.idl',
       'crypto/Key.idl',
       'crypto/SubtleCrypto.idl',
       'crypto/WorkerCrypto.idl',
       'device_orientation/DeviceAcceleration.idl',
       'device_orientation/DeviceMotionEvent.idl',
       'device_orientation/DeviceOrientationEvent.idl',
       'device_orientation/DeviceRotationRate.idl',
+      'encoding/TextDecoder.idl',
+      'encoding/TextEncoder.idl',
       'encryptedmedia/MediaKeyMessageEvent.idl',
       'encryptedmedia/MediaKeyNeededEvent.idl',
       'encryptedmedia/MediaKeys.idl',
       'encryptedmedia/MediaKeySession.idl',
       'filesystem/DOMFileSystem.idl',
       'filesystem/DOMFileSystemSync.idl',
       'filesystem/DirectoryEntry.idl',
       'filesystem/DirectoryEntrySync.idl',
       'filesystem/DirectoryReader.idl',
       'filesystem/DirectoryReaderSync.idl',
@@ skipping 211 matching lines @@
       'device_orientation/DeviceRotationRate.cpp',
       'device_orientation/DeviceRotationRate.h',
       'device_orientation/DeviceSensorEventController.cpp',
       'device_orientation/DeviceSensorEventController.h',
       'device_orientation/DeviceSensorEventDispatcher.cpp',
       'device_orientation/DeviceSensorEventDispatcher.h',
       'device_orientation/NewDeviceOrientationController.cpp',
       'device_orientation/NewDeviceOrientationController.h',
       'donottrack/NavigatorDoNotTrack.cpp',
       'donottrack/NavigatorDoNotTrack.h',
+      'encoding/TextDecoder.cpp',
+      'encoding/TextDecoder.h',
+      'encoding/TextEncoder.cpp',
+      'encoding/TextEncoder.h',
       'encryptedmedia/MediaKeyMessageEvent.cpp',
       'encryptedmedia/MediaKeyMessageEvent.h',
       'encryptedmedia/MediaKeyNeededEvent.cpp',
       'encryptedmedia/MediaKeyNeededEvent.h',
       'encryptedmedia/MediaKeys.cpp',
       'encryptedmedia/MediaKeys.h',
       'encryptedmedia/MediaKeySession.cpp',
       'encryptedmedia/MediaKeySession.h',
       'filesystem/DOMFilePath.cpp',
       'filesystem/DOMFilePath.h',
@@ skipping 480 matching lines @@
       'indexeddb/IDBKeyPathTest.cpp',
       'indexeddb/IDBRequestTest.cpp',
       'indexeddb/IDBTransactionTest.cpp',
       'websockets/WebSocketDeflaterTest.cpp',
       'websockets/WebSocketExtensionDispatcherTest.cpp',
       'websockets/WebSocketExtensionParserTest.cpp',
       'websockets/WebSocketPerMessageDeflateTest.cpp',
     ],
   },
 }