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/dom/BUILD.gn

Index: third_party/WebKit/Source/core/dom/BUILD.gn
diff --git a/third_party/WebKit/Source/core/dom/BUILD.gn b/third_party/WebKit/Source/core/dom/BUILD.gn
index 05345e2abb1dcf83c65b1492eb4fd23eb98ab228..04c77b67bcce59bca8768e9fe6191c21744c8866 100644
--- a/third_party/WebKit/Source/core/dom/BUILD.gn
+++ b/third_party/WebKit/Source/core/dom/BUILD.gn
@@ -12,10 +12,12 @@ blink_core_sources("dom") {
     "AXObjectCache.h",
     "AnimationWorkletProxyClient.h",
     "Attr.cpp",
+    "Attr.h",
     "AttributeCollection.h",
     "CDATASection.cpp",
     "CDATASection.h",
     "CSSSelectorWatch.cpp",
+    "CSSSelectorWatch.h",
     "CharacterData.cpp",
     "ChildFrameDisconnector.cpp",
     "ChildFrameDisconnector.h",
@@ -40,6 +42,7 @@ blink_core_sources("dom") {
     "CompositorWorkerProxyClient.cpp",
     "CompositorWorkerProxyClient.h",
     "ContainerNode.cpp",
+    "ContainerNode.h",
     "ContextFeatures.cpp",
     "ContextFeatures.h",
     "ContextLifecycleNotifier.cpp",
@@ -57,6 +60,7 @@ blink_core_sources("dom") {
     "DOMException.cpp",
     "DOMException.h",
     "DOMImplementation.cpp",
+    "DOMImplementation.h",
     "DOMMatrix.cpp",
     "DOMMatrix.h",
     "DOMMatrixReadOnly.cpp",
@@ -97,6 +101,7 @@ blink_core_sources("dom") {
     "DocumentEncodingData.cpp",
     "DocumentEncodingData.h",
     "DocumentFragment.cpp",
+    "DocumentFragment.h",
     "DocumentFullscreen.cpp",
     "DocumentFullscreen.h",
     "DocumentInit.cpp",
@@ -107,6 +112,7 @@ blink_core_sources("dom") {
     "DocumentOrderedList.cpp",
     "DocumentOrderedList.h",
     "DocumentOrderedMap.cpp",
+    "DocumentOrderedMap.h",
     "DocumentParser.cpp",
     "DocumentParser.h",
     "DocumentParserTiming.cpp",
@@ -120,6 +126,7 @@ blink_core_sources("dom") {
     "DocumentTiming.cpp",
     "DocumentTiming.h",
     "DocumentType.cpp",
+    "DocumentType.h",
     "Element.cpp",
     "Element.h",
     "ElementData.cpp",
@@ -199,6 +206,7 @@ blink_core_sources("dom") {
     "NameNodeList.cpp",
     "NameNodeList.h",
     "NamedNodeMap.cpp",
+    "NamedNodeMap.h",
     "Node.cpp",
     "NodeChildRemovalTracker.cpp",
     "NodeChildRemovalTracker.h",
@@ -223,6 +231,7 @@ blink_core_sources("dom") {
     "NthIndexCache.h",
     "ParentNode.h",
     "PendingScript.cpp",
+    "PendingScript.h",
     "PresentationAttributeStyle.cpp",
     "PresentationAttributeStyle.h",
     "ProcessingInstruction.cpp",
@@ -230,6 +239,7 @@ blink_core_sources("dom") {
     "PseudoElement.cpp",
     "PseudoElementData.h",
     "QualifiedName.cpp",
+    "QualifiedName.h",
     "Range.cpp",
     "RawDataDocumentParser.h",
     "RemoteSecurityContext.cpp",
@@ -269,6 +279,7 @@ blink_core_sources("dom") {
     "SinkDocument.cpp",
     "SinkDocument.h",
     "SpaceSplitString.cpp",
+    "SpaceSplitString.h",
     "StaticNodeList.h",
     "StaticRange.cpp",
     "StaticRange.h",
@@ -286,6 +297,7 @@ blink_core_sources("dom") {
     "StyleSheetCollection.cpp",
     "StyleSheetCollection.h",
     "SuspendableObject.cpp",
+    "SuspendableObject.h",
     "SynchronousMutationNotifier.cpp",
     "SynchronousMutationNotifier.h",
     "SynchronousMutationObserver.cpp",