Add missing header files to GN files

third_party/WebKit/Source/core/html/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/split_static_library.gni")
 import("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("html") {
   split_count = 5
 
@@ skipping 426 matching lines @@
     "parser/HTMLTreeBuilderSimulator.h",
     "parser/HTMLViewSourceParser.cpp",
     "parser/HTMLViewSourceParser.h",
     "parser/InputStreamPreprocessor.h",
     "parser/MarkupTokenizerInlines.h",
     "parser/NestingLevelIncrementer.h",
     "parser/ParserSynchronizationPolicy.h",
     "parser/PreloadRequest.cpp",
     "parser/PreloadRequest.h",
     "parser/ResourcePreloader.cpp",
+    "parser/ResourcePreloader.h",
     "parser/TextDocumentParser.cpp",
     "parser/TextDocumentParser.h",
     "parser/TextResourceDecoder.cpp",
     "parser/TextResourceDecoder.h",
     "parser/TokenizedChunkQueue.cpp",
     "parser/TokenizedChunkQueue.h",
     "parser/XSSAuditor.cpp",
     "parser/XSSAuditor.h",
     "parser/XSSAuditorDelegate.cpp",
     "parser/XSSAuditorDelegate.h",
@@ skipping 54 matching lines @@
     "track/TextTrackCue.cpp",
     "track/TextTrackCue.h",
     "track/TextTrackCueList.cpp",
     "track/TextTrackCueList.h",
     "track/TextTrackKindUserPreference.h",
     "track/TextTrackList.cpp",
     "track/TextTrackList.h",
     "track/TrackBase.cpp",
     "track/TrackBase.h",
     "track/TrackEvent.cpp",
+    "track/TrackEvent.h",
     "track/TrackListBase.h",
     "track/VideoTrack.cpp",
     "track/VideoTrack.h",
     "track/VideoTrackList.cpp",
     "track/VideoTrackList.h",
     "track/vtt/BufferedLineReader.cpp",
     "track/vtt/BufferedLineReader.h",
     "track/vtt/VTTCue.cpp",
     "track/vtt/VTTCue.h",
     "track/vtt/VTTElement.cpp",
     "track/vtt/VTTElement.h",
     "track/vtt/VTTParser.cpp",
     "track/vtt/VTTParser.h",
     "track/vtt/VTTRegion.cpp",
     "track/vtt/VTTRegion.h",
     "track/vtt/VTTScanner.cpp",
     "track/vtt/VTTScanner.h",
     "track/vtt/VTTToken.h",
     "track/vtt/VTTTokenizer.cpp",
     "track/vtt/VTTTokenizer.h",
   ]
 
   configs += [
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     "//build/config/compiler:no_size_t_to_int_warning",
   ]
 }