Add missing .h files to .gn files that have a .cc file next to it in the gn file already.

third_party/WebKit/Source/core/editing/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("//third_party/WebKit/Source/core/core.gni")
 
 blink_core_sources("editing") {
   split_count = 5
   sources = [
     "CaretDisplayItemClient.cpp",
     "CaretDisplayItemClient.h",
     "CompositionUnderline.cpp",
     "CompositionUnderline.h",
     "DOMSelection.cpp",
     "DOMSelection.h",
     "DragCaret.cpp",
     "DragCaret.h",
     "EditingBehavior.cpp",
     "EditingBehavior.h",
     "EditingStrategy.cpp",
     "EditingStrategy.h",
     "EditingStyle.cpp",
+    "EditingStyle.h",
     "EditingStyleUtilities.cpp",
     "EditingStyleUtilities.h",
     "EditingUtilities.cpp",
     "EditingUtilities.h",
     "Editor.cpp",
     "EditorKeyBindings.cpp",
     "EphemeralRange.cpp",
     "EphemeralRange.h",
     "FrameCaret.cpp",
     "FrameCaret.h",
     "FrameSelection.cpp",
+    "FrameSelection.h",
     "GranularityStrategy.cpp",
+    "GranularityStrategy.h",
     "InputMethodController.cpp",
     "InputMethodController.h",
     "PendingSelection.cpp",
     "PendingSelection.h",
     "PlainTextRange.cpp",
     "PlainTextRange.h",
     "Position.cpp",
     "Position.h",
     "PositionIterator.cpp",
     "PositionIterator.h",
@@ skipping 12 matching lines @@
     "SelectionModifier.cpp",
     "SelectionModifier.h",
     "SelectionTemplate.cpp",
     "SelectionTemplate.h",
     "SelectionType.h",
     "SurroundingText.cpp",
     "SurroundingText.h",
     "TextAffinity.cpp",
     "TextAffinity.h",
     "VisiblePosition.cpp",
+    "VisiblePosition.h",
     "VisibleSelection.cpp",
+    "VisibleSelection.h",
     "VisibleUnits.cpp",
+    "VisibleUnits.h",
     "commands/AppendNodeCommand.cpp",
     "commands/AppendNodeCommand.h",
     "commands/ApplyBlockElementCommand.cpp",
     "commands/ApplyBlockElementCommand.h",
     "commands/ApplyStyleCommand.cpp",
     "commands/ApplyStyleCommand.h",
     "commands/BreakBlockquoteCommand.cpp",
     "commands/BreakBlockquoteCommand.h",
     "commands/CompositeEditCommand.cpp",
     "commands/CompositeEditCommand.h",
@@ skipping 61 matching lines @@
     "commands/TypingCommand.h",
     "commands/UndoStack.cpp",
     "commands/UndoStack.h",
     "commands/UndoStep.cpp",
     "commands/UndoStep.h",
     "commands/UnlinkCommand.cpp",
     "commands/UnlinkCommand.h",
     "commands/WrapContentsInDummySpanCommand.cpp",
     "commands/WrapContentsInDummySpanCommand.h",
     "iterators/BackwardsCharacterIterator.cpp",
+    "iterators/BackwardsCharacterIterator.h",
     "iterators/BackwardsTextBuffer.cpp",
     "iterators/BackwardsTextBuffer.h",
     "iterators/BitStack.cpp",
+    "iterators/BitStack.h",
     "iterators/CharacterIterator.cpp",
+    "iterators/CharacterIterator.h",
     "iterators/ForwardsTextBuffer.cpp",
     "iterators/ForwardsTextBuffer.h",
     "iterators/FullyClippedStateStack.cpp",
+    "iterators/FullyClippedStateStack.h",
     "iterators/SearchBuffer.cpp",
     "iterators/SearchBuffer.h",
     "iterators/SimplifiedBackwardsTextIterator.cpp",
+    "iterators/SimplifiedBackwardsTextIterator.h",
     "iterators/TextBufferBase.cpp",
     "iterators/TextBufferBase.h",
     "iterators/TextIterator.cpp",
     "iterators/TextIterator.h",
     "iterators/TextIteratorBehavior.cpp",
     "iterators/TextIteratorBehavior.h",
     "iterators/TextIteratorTextState.cpp",
     "iterators/TextIteratorTextState.h",
     "iterators/TextSearcherICU.cpp",
     "iterators/TextSearcherICU.h",
     "iterators/WordAwareIterator.cpp",
+    "iterators/WordAwareIterator.h",
     "markers/DocumentMarker.cpp",
     "markers/DocumentMarker.h",
     "markers/DocumentMarkerController.cpp",
     "markers/DocumentMarkerController.h",
     "markers/RenderedDocumentMarker.h",
     "serializers/HTMLInterchange.cpp",
     "serializers/HTMLInterchange.h",
     "serializers/MarkupAccumulator.cpp",
     "serializers/MarkupAccumulator.h",
     "serializers/MarkupFormatter.cpp",
@@ skipping 87 matching lines @@
     "spellcheck/IdleSpellCheckCallbackTest.cpp",
     "spellcheck/SpellCheckTestBase.cpp",
     "spellcheck/SpellCheckTestBase.h",
     "spellcheck/SpellCheckerTest.cpp",
     "state_machines/BackspaceStateMachineTest.cpp",
     "state_machines/BackwardCodePointStateMachineTest.cpp",
     "state_machines/BackwardGraphemeBoundaryStateMachineTest.cpp",
     "state_machines/ForwardCodePointStateMachineTest.cpp",
     "state_machines/ForwardGraphemeBoundaryStateMachineTest.cpp",
     "state_machines/StateMachineTestUtil.cpp",
+    "state_machines/StateMachineTestUtil.h",
     "state_machines/StateMachineUtilTest.cpp",
   ]
 
   configs += [
     "//third_party/WebKit/Source/core:blink_core_pch",
     "//third_party/WebKit/Source:config",
     "//third_party/WebKit/Source:inside_blink",
   ]
 
   deps = [
     "//testing/gmock",
     "//testing/gtest",
     "//third_party/WebKit/Source/core:core",
   ]
 }